Well, the computer should have adequate performance.
Does it always stop at the same file? And if so, the full path and name of the file might assist those who know more about these things than me.
What scan settings are you using? Normally, for a first scan, I'd use "standard scan'' and not enable scanning archives.
It would be a good idea to run a disk cleanup before scanning, to reduce the number of unnecessary files scanned. (I find Ccleaner good for that job.)
Also try running the AVG remover,
http://www.avg.com/download-tools which will remove any AVG leftovers, that might be interfering. (Do this first.)