Run a scan with HijackThis. Check each of the following and hit 'Fix checked' (after checking them) if they still exist (make sure not to miss any):
F2 - REG:system.ini: UserInit=userinit.exe,C:\WINDOWS\system\svchost.exe
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
Reboot to safe mode:
Begin tapping the F8 key every few seconds as the system boots up until the screen offering
the Safe Mode option appears (if Windows launches before you can choose a Safe Mode, restart your
computer and try again).
SHOW HIDDEN FILES
1. Click Start button, then go to Programs, Accessories and click on Windows Explorer.
2. Select the Tools menu and click Folder Options.
3. Select the View Tab.
4. Under the "Hidden files and folders" heading please check Show hidden files and folders.
5. Uncheck the Hide protected operating system files (Recommended) option.
6. Click Yes to confirm.
7. Click OK.
Delete this file ->
C:\WINDOWS\system\svchost.exe
NB. You have a legal Microsoft svchost.exe file, located here:
C:\WINDOWS\system32\svchost.exe << don´t delete it
Reboot normally, post new hijackthis log (attacht it) and tell how things are running now