Scans Alternatingly Stopping Prematurely & Going on Forever

About two weeks ago, I noticed that both my Quick and Full scans were ending prematurely after about a minute’s worth of runtime. The yellow progress bar showing the percentage of completion never left 0% in either case. This has continued each time I’ve tried running any scan (except for the Boot scan, which I never run unless prompted) ever since. I’ve still been able to get updates regularly, with no sign of problem. But I have not been able to perform a complete scan at all since then.

If a scan ends and I immediately go back and restart it without closing out of the program, the scan will run, well… forever. I left it going overnight and it’s been running for over seventeen hours at the moment. The yellow progress bar is still at 0%. When I click “stop”, nothing happens; the scan continues.

In each of these scans, there has never been any threat or infected file found. I also use Super AntiSpyware and Malware Bytes and neither or them have indicated that I have any sort of threat, infection, virus, worm, etc.

As of writing this, this is the file that the Quick Scan is stuck on:
SVC:xmlprov>C:\WINDOWS\System32/svchost.exe

And this is what the Full Scan is stuck on:
C:\WINDOWS$NtServicePackUninstall$\reg00094

I thought that registration might have something to do with it, because I had about forty days left on mine. So I tried to register, and I received a message that said an error occurred. I tried again, same thing. So I uninstalled AVAST and then re-installed, then registered. But I’m still having the same problem with the scan now.

Any help on figuring this out would be great. Thanks.

Remove avast, run the uninstall utillity, reboot, run CCleaner have it fix everything it finds, reboot, install a fresh copy of avast.

Thank you very much; I’ll try that.