Problems Importing hdv .mpeg into CS5 - audio unsync

Hi all, my name is Laura, I'm new here, and I'd be so grateful if someone can give me a hint on this problem:

I've been asked to edit a video, and they've given me:
-a folder that contains four files: two .mpeg video files wich ranges from 8gb to 11gb (around 50 minutes each), and two .xmp files with the same name as the others.

-These are HDV video files, shot in 1440x1080i, 1.33 pixel aspect ratio, 50fps, pal. Recorded (I'm not 100% sure) with a Sony.

-The thing is, I usually edit HDV, but never .mpeg files. They usually give me .m2t.

-So, with Premiere Pro Cs5, the first problem I've encoutered was that importing these files was extreeemely slow. I imagine that the file size might not have helped with that.

-So, finally I imported them.. BUT, once I started editing I noticed that the audio was NOT in sync!

-I checked the footage by opening it with a video player outside premiere, and the audio was in sync, so it's something that happens when I put those .mpeg inside premiere.

-What should I do? The guy who recorded this told me that he downloaded the material using premiere, and that it created by default those .mpeg files. Do I need to tell him I need the material in other format? Am I doing something wrong?
I'm really lost here!
Sorry for the long post!

I can't tell you the exact version of the cs5 i'm using, because I'm not in that computer right now (it's not my computer either), but I think it has the latest actualizations.

In another forum they recommended asking the guy who taped this to download the material as .m2t... is that something the camera guy can do? Or the only option he has (as he told me) is to download as .mpeg?