Choppy video, no idea how to fix

[Taika]

I want to stress I'm only tech-savvy to a point so please bear with me.

I downloaded Premiere Elements today, imported a video file (MPEG, 25FPS) and the quality is awful; very choppy and the playback line on the timeline keeps jumping back on itself. I haven't done anything except import media; no effects, transitions, rendering, etc. I've been googling for solutions for the past four hours but everything which has popped up tends to be strictly for Premiere Pro and I can't find the same solutions in Elements.

I disabled the default audio hardware in the edit menu, which made the audio come through nice and clear, but the video is still choppy and not keeping up with the audio. I've also tried importing different file types but the only one which ran relatively smoothly was an mp4 - still a little choppy though. I tried altering the preset on new projects, but this is where I struggle because I don't know all the tecnicalities between what makes certain file types different or which one an MPEG at 25FPS falls into. In any case, every preset I tried made no difference and the video was still choppy.

I checked my PC system requirements and everything appears to be fine; my PC is old but still in very good shape with loads of free memory. All the file types I tried play back perfectly on numerous media players and can be edited no problem in Windows Movie Maker.

I'd really appreciate any help with this. I'm not a newbie to video editing but I've only ever done it on less powerful softwares, so I know how to edit but I'm not too good with terminology/presets etc. I really don't have a clue how to fix this. All I want is for the video to run smoothly and would hate to think I've just spent a lot of money on something my PC won't let me use.

Thanks in advance, any help greatly appreciated!

[Steve Grisetti]

Which processor does your PC have with how much RAM? What operating system are you running?

An MPEG is rather unusual format to be editing these days. Where did it come from? Do you know this MPEGs resolution?

Finally, when you added this MPEG to the timeline of a new project, did you see a yellow orange "render" line above this clip?