Buffering issues when viewing

I'm relatively new to XBMC so please bear with me.

I'm running XBMC on a 64 bit Dell E5800 @ 3.2GHZ with 3gb of ram. My video card and sound card are the default ones that came with the computer I bought about a year ago. The computer has an HDMI out that I use to watch XBMC on my big screen.

The problem is, when watching certain movies (usually MKV files), XBMC will buffer, then quit out to the main menu at the exact same point during the movie. This does not happen once. It happens at several points during the movie(s) like clockwork. It will always buffer/quit at the same points during a movie.

At first I thought it was the movie(s), but it seems to happen too frequently and during different movies to be the movie files. This happened using the latest version of Eden, and the latest version of Frodo. Here is the complete log file from Frodo.

I'm not really able to look at the log file and tell exactly what's happening. Hoping someone can help pinpoint the issue.

I would really appreciate some assistance with this. Thanks.