on my daughters pc, it keeps trying to send hundreds of emails. I've ran avg, panda, ZA and avast, all say clean, what can I do?

the emails all say their from different people to different people. obviously Im infected.

Hmmm, that's strange. Did you run the virus scans in safe mode? If you hit ctrl+alt+del do you see any strange filenames running?

I would say get the 30 day free trial of NOD32 and install it, as well as update the virus defs, then reboot to SAFE MODE and run AV scans

That is weird that it won't pick up on anything
Defiantly try it in safe mode
If that don't work try a live cd with a virus scanner

I was thinking it could be an IM nasty as those do send out mass e-mailings amongst other things and are apparently easy to get.

First, disconnect that computer from the Internet! Any files you need you can get on your computer and then use a flash drive to put them on your daughter's computer. That virus is probably useless without an Internet connection.

Second, open the task manager and start looking at all of the processes running. If you are not sure what they are type them into Google or Yahoo search like this: "program.exe" and they will give you the results. Stop whatever programs that are not necessary to the system.

Third, Safe Mode like everyone else has already said.

Good luck.

Also have a nosey in the Add/Remove Programs in case the virus was installed by a little program she has downloaded and installed, after you have run the virus scan it would also be worth running a full adware/spyware scan with something such as Windows Defender.