OptProReminder?

Why doesn’t Avast pick up and delete OptProReminder?

No security program have 100% detection

it is classed as PUP = not virus / Possible Unwanted Program …usually crap that comes bundled with freeware downloads
avast PUP detection is default off exept for in Boot Scan …

do you need help removing it?..if so follow this guide http://forum.avast.com/index.php?topic=53253.0
attach Malwarebytes and OTL log, when done a malware expert will assist you