"Windows Genuine Advantage Validation v18.104.22.168" is the name of a legitimate Windows component so this may be a false positive
AVG should list the file it thinks is infected in the Infections tab of the scan results. From there you can locate the file on your hard drive and upload it to VirusTotal.com
to have the file scanned by 40 different anti-virus tools and view the results. Alternatively you may upload it here
and I can take a look at it to make sure it's the real Windows file.
You may also want to scan your computer with a different tool to get a second opinion (since no anti-virus program is perfect.) Trend Micro offers a quick scanner which is available here: Trend Micro Housecall
(you want the 32-bit version.) Another good, but harder to use, scanner is Microsoft's Offline System Sweeper
. It creates a CD or USB drive (blank CDs/USB drives provided by you) from which your computer can boot. It then scans your computer and offers to fix any malicious software it finds. This method is particularly effective against really nasty malware, but is also good for checkups. (As with Housecall, you'd want to get the 32-bit version.)
Edited by Andrew, 28 December 2011 - 03:44 PM.