I don't know if any of those might somehow slow the scan down as they too might be trying to scan a file that avast is trying to open for scanning, have you installed any of them recently?
Until this latest round of program updates only full scans were recorder in the logs (that may well have been different for Pro anyway), but the latest should show the last scan in the Interface and I assume in the Pro logs.
Perhaps you should try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. You need to be on-line to do this.
If that doesn't work try, uninstall, reboot, install, reboot.
It would probably be best to download the latest version of avast and save it to your HDD, somewhere you can find it again. Use that when you reinstall.
Reference the possible false positive, lets not get away from what you started the thread about, the avast scan, it becomes confusing when there are multiple issues in the thread, in effect hijacking it yourself on to another topic.
I suggest you start a new topic for the possible FP with more information on the virus name and where it was located and why you feel it is a false positive.