Please tell us the full details of that MPEG file. This ARTICLE will give you some background on what can be inside an MPEG, AVI or MOV file. It will also tell you how to gather the necessary info. The file extension is only an indicator of a "wrapper."
Good luck, and please post the details on that file,
A couple of things to consider:
It's possible that this large mpeg file is corrupt at the point that the Import fails.
See if the files plays okay to completion using one of the media players on your PC (like Windows Media Player).
If okay, convert to DV-AVI prior to import into PE.
Use this link for free conversion options:
Once converted successfully, chances are excellant this will cure any issues with PE...