Windows Vista 'not genuine' after Boot-Time Scan

After downloading, installing, and running Avast Free Antivirus Boot-Time Scan for the first time and then starting Windows Vista Home Premium 2 a small message appeared in the lower right hand corner of the desktop as follows:
"
Windows Vista ™
Build 6002
This copy of Windows is not genuine
"
Could this have been caused by the removal of one of the viruses found? I checked with Microsoft and they indicate my copy of Vista is legit. How can I remove this persistent text?

Try this in IE: http://www.microsoft.com/genuine/validate/validatenow.aspx

Yes It could have depending on what was infected…and if it was properly all cleaned out
Also is this “The Copy of Windows IS Not Genuine” stuck every time your computer starts?
What other security software do you have on this computer…And which Firewall are you using?
Do You have Malwarebutes or Superantispyware free scanners?..Did you use something like CCleaner to fix all registy issues and any leftovers that aren’t needed? Which Antivirus was on before you downloaded Avast free, and how did you uninstall it?
Keep us updated…Always somebody here to offer help…
Cheers and safe surfing!!!