Odd I've just had the same thing happen with SWMBO laptop, it would.

Using outlook became impossible and after about 10 mins it would lose the wireless signal until it was rebooted.

Even in safe mode trying to run regedit caused the same thing to happen.No virus / malware / spyware detected.

Repair of XP install didn't work and I had to do a complete install of windows again to sort it out.

Sounds like bad news then
Exactly the same happened here to my wife's laptop. Had to format and do a full re-install

Can you execute 'cmd' from the run prompt? If not then it looks like you're not alone. Another recent report here too.

Would be interested to know what the cause is.

No - I cannot execute cmd from the Run prompt.

Does look like you were in the same boat as we were, which means a re-install.

You could try a repair in the first instance, guide here otherwise a clean reinstall.

I didn't format, just got the install to delete the windows directory.

This has got to be virus or malware chaps, does any one now if the issue has been reported to any of the major AV & AS co's? I haven't been on for the last 24hrs, so got some catching up to do.
@fulbourn
Go to MMM (Manage my Mail) in the member centre and check your settings to see if identified spam is still set to be tagged. If so Post some headers from a obvious spam message (put xxx.yyy over your name.domain part of your e-mail address).

Anyone had any luck with a fix?

I'm sure it's neither. I scanned with Kaspersky online, trend on line and Clamwin as well as malwarebytes.

SWMBO's email is scanned and Avast was installed when all that happened. Seems to be something odd going on.

I never found anything either and I did a full scan for virus and malware, with the pc's programmes and online scans.