Same thing happened to me, but while looking at where it was stucked I found out it was looking for files i deleted while the plugin was scanning.
So while it scans and gives you the Scan/Read Error, if you go and delete these files then it tries to scan them again. Plugin wont find them so it goes into a loop i guess.
The second time i runned scan it worked like a charm!
At least thats what happened to my case!