Avast Free full system scan suspends, won't complete

I run a schedule full system scan every Sunday about 6pm, and every Sunday (usually about 9pm) when I get back to my computer, the scan is suspended - different percent complete every time, today it got to 91%. There is nothing on the screen showing what file was being processed when it suspended, and there are so many files in the log directory I don’t know which one to look in. The quick scans I do on other nights complete fine.

I have the current version with updates, Windows 8, Online Armor firewall, and Emsisoft Antimalware - I have used the exclusions in each one’s setup to exclude the directory trees of the other two, but maybe there is some further conflict I don’t know about… I searched a little for answers and only found the suggestion to uninstall and reinstall, and a comment that for at least one person that did not help.

Why using the Online Armor firewall while windows already has one?
What exact version of avast do you have?
Emsisoft Antimalware is a av also.
Never run or have two av’s at the same time.

I don't know which one to look in.
Look at the date of the files.