Geezzz!!! I am finding it more difficult to get rid of some adware nowadays.
I have a pc running WIN XP that keeps having 680180.net pop-ups appearing and we cannot check Hotmail, as soon as we go into Hotmail IE6 closes down. I am sure it is as a result of this 680180 problem.
I have run Ad-aware and Spybot and fixed all problems, have ran an online virus check and AVG is installed and no virus's are detected.
I have run Hijack this to give the following:

Logfile of HijackThis v1.97.7
Scan saved at 12:13:34, on 12/08/2004
Platform: Windows XP SP1 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\LEXBCES.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\LEXPPS.EXE
C:\PROGRA~1\Grisoft\AVG7\avgamsvr.exe
C:\PROGRA~1\Grisoft\AVG7\avgupsvc.exe
C:\WINDOWS\system32\cisvc.exe
C:\WINDOWS\System32\nvsvc32.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\SYSTEM32\ZoneLabs\vsmon.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\System32\DSentry.exe
C:\Program Files\Roxio\Easy CD Creator 5\DirectCD\DirectCD.exe
C:\Program Files\Alcatel\SpeedTouch USB\Dragdiag.exe
C:\Program Files\Messenger Plus! 2\MsgPlus.exe
C:\Program Files\Common Files\Real\Update_OB\realsched.exe
C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe
C:\PROGRA~1\Grisoft\AVG7\avgcc.exe
C:\Program Files\MSN Apps\Updater\01.02.0002.1001\en-gb\msnappau.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Program Files\Digital Line Detect\DLG.exe
C:\Program Files\Ulead Systems\Ulead Photo Express 4.0 SE\CalCheck.exe
C:\Program Files\MSN Messenger\msnmsgr.exe
C:\WINDOWS\system32\cidaemon.exe
C:\WINDOWS\system32\cidaemon.exe
C:\Program Files\Internet Explorer\IEXPLORE.EXE
E:\Spyware\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.co.uk/
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.euro.dell.com/countries/uk/enu/gen/default.htm
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Tiscali 10.0
R3 - URLSearchHook: (no name) - {00D6A7E7-4A97-456f-848A-3B75BF7554D7} - (no file)
O2 - BHO: (no name) - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 6.0\Reader\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {0A6AD913-CFCE-4D15-93A6-9DD2E21893F0} - C:\WINDOWS\System32\shsit.dll
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: (no name) - {9394EDE7-C8B5-483E-8773-474BF36AF6E4} - C:\Program Files\MSN Apps\ST\01.02.0002.1001\en-xu\stmain.dll
O2 - BHO: (no name) - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar2.dll
O2 - BHO: (no name) - {BDBD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Program Files\MSN Apps\MSN Toolbar\01.02.0002.1001\en-gb\msntb.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O3 - Toolbar: MSN - {BDAD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Program Files\MSN Apps\MSN Toolbar\01.02.0002.1001\en-gb\msntb.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar2.dll
O4 - HKLM\..\Run: [DwlClient] C:\Program Files\Common Files\Dell\EUSW\Support.exe
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [DVDSentry] C:\WINDOWS\System32\DSentry.exe
O4 - HKLM\..\Run: [AdaptecDirectCD] "C:\Program Files\Roxio\Easy CD Creator 5\DirectCD\DirectCD.exe"
O4 - HKLM\..\Run: [SpeedTouch USB Diagnostics] "C:\Program Files\Alcatel\SpeedTouch USB\Dragdiag.exe" /icon
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [MessengerPlus2] "C:\Program Files\Messenger Plus! 2\MsgPlus.exe"
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Common Files\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [MSNSysRestore] C:\WINDOWS\System32\pc32.exe bg
O4 - HKLM\..\Run: [shsitc] C:\WINDOWS\System32\shsitc.exe
O4 - HKLM\..\Run: [Zone Labs Client] "C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe"
O4 - HKLM\..\Run: [AVG7_CC] C:\PROGRA~1\Grisoft\AVG7\avgcc.exe /STARTUP
O4 - HKLM\..\Run: [msnappau] "C:\Program Files\MSN Apps\Updater\01.02.0002.1001\en-gb\msnappau.exe"
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [MessengerPlus2] "C:\Program Files\Messenger Plus! 2\MsgPlus.exe" /WinStart
O4 - Global Startup: Digital Line Detect.lnk = ?
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O4 - Global Startup: Ulead Photo Express 4.0 SE Calendar Checker .lnk = C:\Program Files\Ulead Systems\Ulead Photo Express 4.0 SE\CalCheck.exe
O8 - Extra context menu item: &Google Search - res://c:\program files\google\GoogleToolbar2.dll/cmsearch.html
O8 - Extra context menu item: Backward Links - res://c:\program files\google\GoogleToolbar2.dll/cmbacklinks.html
O8 - Extra context menu item: Cached Snapshot of Page - res://c:\program files\google\GoogleToolbar2.dll/cmcache.html
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~3\Office10\EXCEL.EXE/3000
O8 - Extra context menu item: Similar Pages - res://c:\program files\google\GoogleToolbar2.dll/cmsimilar.html
O8 - Extra context menu item: Translate into English - res://c:\program files\google\GoogleToolbar2.dll/cmtrans.html
O9 - Extra button: Messenger (HKLM)
O9 - Extra 'Tools' menuitem: Messenger (HKLM)
O15 - Trusted Zone: *.passport.com
O15 - Trusted Zone: *.passport.net
O16 - DPF: {00B71CFB-6864-4346-A978-C0A14556272C} (Checkers Class) - http://messenger.zone.msn.com/binary/msgrchkr.cab
O16 - DPF: {02BF25D5-8C17-4B23-BC80-D3488ABDDC6B} (QuickTime Object) - http://www.apple.com/qtactivex/qtplugin.cab
O16 - DPF: {166B1BCA-3F9C-11CF-8075-444553540000} (Shockwave ActiveX Control) - http://download.macromedia.com/pub/shockwave/cabs/director/sw.cab
O16 - DPF: {2359626E-7524-4F87-B04E-22CD38A0C88C} (ICSScannerLight Class) - http://download.zonelabs.com/bin/free/cm/ICSCM.cab
O16 - DPF: {2917297F-F02B-4B9D-81DF-494B6333150B} (Minesweeper Flags Class) - http://messenger.zone.msn.com/binary/MineSweeper.cab
O16 - DPF: {41F17733-B041-4099-A042-B518BB6A408C} - http://a1540.g.akamai.net/7/1540/52...pple.com/bonnie/us/win/QuickTimeInstaller.exe
O16 - DPF: {4E888414-DB8F-11D1-9CD9-00C04F98436A} (Microsoft.WinRep) - https://webresponse.one.microsoft.com/oas/ActiveX/winrep.cab
O16 - DPF: {74D05D43-3236-11D4-BDCD-00C04F9A3B61} (HouseCall Control) - http://a840.g.akamai.net/7/840/537/2004061001/housecall.trendmicro.com/housecall/xscan53.cab
O16 - DPF: {80DD2229-B8E4-4C77-B72F-F22972D723EA} (AvxScanOnline Control) - http://www.bitdefender.com/scan/Msie/bitdefender.cab
O16 - DPF: {8E0D4DE5-3180-4024-A327-4DFAD1796A8D} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsClient.cab
O16 - DPF: {9A9307A0-7DA4-4DAF-B042-5009F29E09E1} (ActiveScan Installer Class) - http://www.pandasoftware.com/activescan/as5/asinst.cab
O16 - DPF: {AD7FAFB0-16D6-40C3-AF27-585D6E6453FD} -
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab
O16 - DPF: {E5D419D6-A846-4514-9FAD-97E826C84822} (HeartbeatCtl Class) - http://fdl.msn.com/zone/datafiles/heartbeat.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{0E70C3EC-DC59-437D-9362-319BDD433BC8}: NameServer = 194.168.4.100 194.168.8.100
O17 - HKLM\System\CS1\Services\Tcpip\..\{0E70C3EC-DC59-437D-9362-319BDD433BC8}: NameServer = 194.168.4.100 194.168.8.100

I am suspicious of a couple of items in 02 and 04 referring to shsit.dll. but am not sure and don't want to remove them. They don't appear on my pc which is why I am supicious.

Has anyone else come up against this problem and can they help me out?

If you browse to one of these shsit files, right click, go to summary, does the information in there give any indication of the name of this program or a version??

I've googled for shsit, I didn't see any relevant information on those files.

In general, though, I'd say the system looks relatively clean. MSN messenger is always a real pain and useless program, but if you like/use it I guess it should be there. The shsit* entries are the only ones that I too really can't explain.

You need to be more worried about a couple of programs like windows/system32/pc32.exe
You have a Trojan.
Readup here:
http://www.pestpatrol.com/PestInfo/d/divx_updater.asp