Question : *.exe is not a valid Win32 application - but ok in safe mode XP Pro

Booting normally this windows XP Pro SP2 (now SP3) laptop gets to the desktop wallpaper with no icons or toolbars. Starting explorer.exe from task manager generates the error message in the title above. In safe mode all is well. Other appps generate same error eg regedit it isn't specific to an app more like to all exe files.

A repair install with XP Pro SP2 did not fix, nor did repair install wth SP3.

Suggestions where to look for bad registry data or other source of problem ? Don't bother telling me to format it :-)

Answer : *.exe is not a valid Win32 application - but ok in safe mode XP Pro

Solved - it was caused by Comodo Firewall. I got the desktop icons back by changing the registry entry for userinit to explorer.exe however the *.exe problem remained.

I figured it had to be something that only ran in normal mode so uninstalled first the AV (no change) then the firewall - bingo !

Thanks for the help.