This thread is in the LimeWire (LW) section, but applies to all gnutella users:
WARNING: Viruses on network you should be aware of! (click on link); ie: more good advice, & "if" you should be unlucky to make the mistake of downlding something you didn't intend to downld such as making a mistake with file sizes, then there's also lots of advice about how to rid yourself of it.
I guess someone voting in this poll above reactivated this oldish thread.