Have you a HP printer attached? Disconnect it, boot into safe mode and uninstall the printer.

If that fixes the problem, search HP's site for a fix or patch.

Turn off virtual memory [aka swap file, page file], reboot and try defragging. Turn virtual memory on again afterwards.

It's probably worth your while running another A-V like AVG and a couple of anti-malware programs like AdAware and SpyBot, just to more or less eliminate it being a problem on your side.

Do you...

Can you paste an example here for us to look at?

Are you using WinXP?

It can be done--do a search for "dual boot."

You'll need to partition your hard drive beforehand, and you should have 256MB RAM and better than around a 1.5GHz processor to be able to use XP...

Any error messages? How far can you get in the shutdown process, what happens at end?

Sounds like a major mess to me :(

Wait and see what others might suggest, but it sounds like you need to format your hard drive and do a clean install of Win XP.

Did you have a dual boot...

Windows64 can use the extra power in the new 64-bit CPUs from AMD and Intel. Windows XP is 32-bit, so it basically can't use the extra.

Win64 is really only useful if you also have 64-bit...

Sarah, has your PC always done this, or did it run fine until recently?

Can you remember making any changes shortly before this started happening, eg installing new hardware or software?

Which version of Windows have you?

Like QKS said, could be a bug at PitStop. I wouldn't worry about unless you have operational problems.

Turn the monitor upside down... Sorry :p

1. Might be a prank. Have a look at the running apps for anyone you don't recognize. I recall a joke program called "australia.exe" did this, maybe...

You've probably done this, but remove and reinsert your keyboard connector at the back of the PC.

wupdater and data1.dat are malware, iirc hijacker and adware.

You need to run some malware removal program to get rid of this. Probably best to Google for it, as these kinds of parasites usually...