I am currently working on a Windows XP PC which gives an error message when it tries to log into the default profile: "A problem is preventing windows from accurately checking the license for this computer. ERROR 0x80004005" This problem sends it back to the welcome screen and any attempt to log in again gives the same message. I have looked around the internet and found 4 possible fixes, all of which I have tried and have not been successful. 1. Replacing %SystemRoot%\System32\secupd.dat %SystemRoot%\System32\oembios.dat %SystemRoot%\System32\oembios.bin 2. Open your computer in safe mode, open a command promt Register the following DLL s it should be in the %system root% \ system32 folder just type the following statements one by one and see you got success information popup regsvr32 licwmi.dll regsvr32 regwizc.dll regsvr32 licdll.dll regsvr32 jscript.dll regsvr32 vbscript.dll regsvr32 msxml.dll regsvr32 shdocvw.dll regsvr32 softpub.dll regsvr32 wintrust.dll regsvr32 initpki.dll regsvr32 dssenh.dll regsvr32 rsaenh.dll regsvr32 gpkcsp.dll regsvr32 sccbase.dll regsvr32 slbcsp.dll regsvr32 cryptdlg.dll then try to restart, I carried this out but it had no effect. 3. In the registry, go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ Windows NT\CurrentVersion\WPAEvents Highlight it and File - Export (as a precaution) then in the right pane double click OOBETimer and very carefully change just the first byte (to say 00) Copy the two files windows\system32\wpa.dbl and wpa.bak to a different folder, and delete them Get on the internet Go to Start - All Programs - Accessories - System Tools - Activate Windows and use Activate on the internet now. This method fails as I cannot get networking in safe mode without it throwing the same logon error. Trying to get in curretly but no combination of options gives me any network so no reactivation. 4. Removing the cryptography keys that can be installed on Dell system amongst others Start the computer. Press the F8 key during startup to start the computer in Safe mode. Start Registry Editor (Regedt32.exe). Delete the following registry keys in the Windows registry: HKEY_USERS\.DEFAULT\Software\Microsoft\Cryptography\Providers HKEY_USERS\S-1-5-20\Software\Microsoft\Cryptography\Providers Quit Registry Editor. Restart the computer. These keys didnt exist on my Windows installation so this could not be done. And people say XP is awesome compared to Vista..