Hi. So I have this movie file, it's an mpeg, and it plays perfectly with K-Lite Mega Codec Pack 3.35. But when I use K-Lite Mega Codec Pack 3.45, 3.50, or 3.53 it only plays the first few minutes then stops. I haven't tried 3.40, so obviously it's something that has been changed or removed from the 3.35 or the 3.40. I'm looking at the change logs and I'm not too sure what it is. I can get it to work if I use VLC though.

There's no reason why it shouldn't work. Do you know what player and codec you use to play the MPEG?
I assume you uninstalled older version before upgrading.
You can use Codec tweak tool or do a custom install to change settings. Did you install anything else that may have caused conflicts?

This is probably related to the mpeg splitters. No matter which splitter you use there will always be some files that won't play nice.

Try disabling the Haali MPEG TS splitter with the Codec Tweak Tool.

If that doesn't work, then go into Media Player Classic options. On the Internal Filters page, enable the MPEG source filter.

I will try what you have suggested. And yes I unistalled the other one, lol. I've tried reformatting my computer installing 3.35 and the MPEG plays. Then I reformat and install another pack and it won't play. 3.35 has something the others don't, I'm sure of it. In the change log Gabest splitter was updated so it may be that, but as I said I will try what has been suggested and see if it works.

The Haali MPEG TS splitter is what has changed. It used to be disabled by default, now it is enabled by default.