I just had a nasty trojan or virus on my Vista PC:

After running several virus and spyware programs, i found out
(indirectly by cheking for an automatically called website) that i had a
TDSS rootkit Virus.

Its not detected by virus programs (for no sensible reason)
Since there is a program that can detect and remove them:

http://support.kaspersky.com/faq/?qid=208280684

I would suggest anyone to testrun this scan.
(ist suplied by Kaspersky)