I am trying to fix a friends lap top - it is running on Windows XP and is a Compaq - Presario X1000 laptop. I was told that it started after some songs were downloaded through limewire. What happens is that when the computer is turned on and you log on a window comes up stating "Windows Defender - Application failed to initialize: 0x800106ba. A problem caused Windows Defender Service to STOP. To start the service, restart your computer or search Help and Support on how to start a service manually."
Every 15 seconds or so everything (including taskbar on bottom and desktop icons disappear only to reappear as if the laptop had just been turned on (because the little icons on the right hand side within the taskbar pop up one by one). I have tried to open My Computer and it does not want to open. There are also free versions of AVG on the computer. I have tried running these free checks and they come back with nothing. I'm not sure where to go from here. I'm not sure if this would be a virus or a device problem? PLEASE help.See, if you can operate computer from Safe Mode.Thats a real problem, could be a Trojan or nasty virus. I had one which acted quite the same, what its doing is restarting explorer, from a predetermined time. This would stop you from REMOVING the virus. MAKING it somewhat invincible.

I would say just BOOT in safe mode too.. If it doesn't work in safe mode tell me what happened..
Kieran