Every now and then - about once every two hours - Explorer.exe will crash and then reload. This is a new install of Xp. I've ran virus scanners, Adaware and scan disc -everything was clean. I have no idea what to do now. I can't have a system this unstable as I need to use it for work

Tony

Had a very similiar problem last year when I ordered a Systemax AMD Athlon 64 system. I immediately wiped the disk and reinstalled WinXP Pro and everything went well for many hours, however immediately after loading the factory software and drivers the system became totally unstable. Needless to say I returned the whole damn thing within 48 hours.

The instability could come from many sources such as hidden or unknown spyware that Ad-Aware and/or Spybot S&D don't currently detect. More likely buggy drivers.

Alot of systems come with BackWeb Lite installed, such crapware makes systems crash and especially Explorer.exe like crazy. Its best to uninstall crapware like that via Add/Remove, Add or Remove and then manually remove the registry entries (its probably not all of them, use Ad-Aware and Spybot S&D to fully eradicate it):
[HKEY_CLASSES_ROOT\BackWeb.Client.ScriptHelper-]
[HKEY_CLASSES_ROOT\BackWeb.FileAccess-7288971]
[HKEY_CLASSES_ROOT\BackWeb.FileAccessViaDir-7288971]
[HKEY_CLASSES_ROOT\BackWeb.FileReplication-7288971]
[HKEY_CLASSES_ROOT\BackWeb.FileReplicationCleanup-7288971]
[HKEY_CLASSES_ROOT\BackWeb.FileReplicationExtension-7288971]
[HKEY_CLASSES_ROOT\BackWeb.VBFileReplicationExtension-7288971]
[HKEY_CLASSES_ROOT\bwpfile]
[HKEY_LOCAL_MACHINE\SOFTWARE\BackWeb]

I had a very similar problem just after installing Windows 2000 Professional - explorer.exe was crashing and restarting itself every few minutes. Some buggy software causes that, in my case so called Anark client was guilty (Anark is an ActiveX plugin to play 3D multimedia content on web-pages, I installed it to watch the presentation of nForce2 chipset on nVidia web-site). After uninstalling it, everything came back to normal. If you're on a fresh install, you probably don't have very much installed, so just uninstall everything one by one until the problem disappears - that's how I fixed it here.

Thanks for the help guys. SP2 solved the problem.