Scan will not complete

You don't mention which version of SAV for Mac you have which would help give a more precise answer.  However I would say:

Step 1:

I'd recommend, if you don't already have it install, upgrading to v9.1...

openforum.sophos.com/.../Sophos-Anti-Virus-for-Mac-Home/SAV-for-Mac-9-1-Preview/td-p/18025

...as that's the last version and has several fixes etc.  It's not been releases to home users yet so you'll have to download and install in manually at the moment.

Once you're on v9.1 test the scan again and see if you experience the problem again.

Step 2:

If the issue is still present you should look in Console for the scan log (for the type of scan you are running) and see what is logged.  The thread below explains where the logs are...

http://openforum.sophos.com/t5/Mac-tools-help/Where-are-the-logs-for-SAV-for-Mac/td-p/16091

Step 3:

Tip: If you are running a 'Scan This Mac' scan you should set up a custom scan and see if that has the same problem.

Scans explained in SAV for Mac: https://www.youtube.com/watch?v=j3SUJFozC2Q

I am having the same problem.  My IOS is 10.9.4 and my SAV version is 9.1.5.  I started with "Scan this Mac" yesterday at 1:00 p.m., and it's now 9:30 a.m. and still running.  There is no progress bar, just a spiraling bar with "calculating..." under it.  Not getting any error messages.  The Console log has over 4000 messages on this scan so far, so it seems to not be stuck, but I'm not privy to desciphering what the log is showing.  Is this the way SAV is supposed to work?

As well, I'm having this issue. I'm running Mac OS X 10.9.4 and using SophosVersion 9.0.11-Threat detection engine: 3.51.0. Initiall I ran a scan that detected three malware on the Mac and peripheral storage devices. I attempted using the "fix-it" button but none of the malware files was removed, so I followed the file trail and removed some files.

Before I did this I followed the recommended action of stopping the "Live Protection".

As I navigated through "Finder" and removed some files, there were files in which the trail was not evident past a point. 

While trying to finish the removal I noted the Sophos was scanning and went to turn off the scan.

The scan would not stop when the "stop scan" prompt was used.

The scan is still stuck at 3/4 of the way through the full scan and there is not a lot I can do except unintstall the Sophos file and re-install, maybe.

Can someone advise on how to uninstall the Spohos software and reinstall in the correct manner? 

I've had issues uninstalling antivirus software in the past and the files left behind on an :unofficial" uninstall cause more issues.

As of today the initial issue stated as a non-progressing antivirus scan and a Sophos program that was not shutting down has morphed into the same issue as the iniital post on this thread. The Sophos software is now posting a message within minutes of scan initiation "scan could not be completed due to an error".