Avast's url:mal (HTMl:RedirME-inf[Trj]) pop-ups won't stop!

I use Avast free, and I've been getting these pop-ups for over a month now, they usually pop up whenever I start my Windows, and then spontaneously (sometimes I get the pop-ups while I'm away from my laptop with no browsers or programs open!).

Am I infected? Is it about "Microsoft certificate revocation list"?

Infection: HTMl:RedirME-inf[Trj]
Process: C:\Windows\System32\svchost.exe

Objects are:

hxxp://crl.microsoft.com/pki/crl/products/MicWinHarComPCA_2008-01-08.crl...

Avast's url:mal (HTMl:RedirME-inf[Trj]) pop-ups won't stop!