Well, I'm not 100% sure because I'm unfamiliar with your anti-virus program (Kaspersky, I'm thinking?) but I found a discussion:
http://www.dslreports.com/foru...
It seems "HEUR" indicates that this was a heuristic test (an educated guess in software, basically) and can find false positives.
I really don't think Google is going to allow malware in the ads they display on their partner sites. I think we're okay here.