[PE9] noise or no sound when exporting

Question

I'm putting together a video from a trip. After a while, my computer started getting slow and Premiere Elements almost instantly showed a memory error when opening my project. So I arranged a faster computer to borrow for a while, which solved the memory problem.
Now I want to share/produce/export my project as a movie, so I can watch it and write down things I want to change. Rendering as an avi results in an "unknown error", other formats seem to work fine apart from the sound. I either get a continuous noise or no sound at all. I literally tested every output possibility in PE9.
I assume it's not the project itself, because I did preliminary exports before which looked and sounded fine. The difference is: those exports where made on my own computer, the one that got to slow in the end. So it's not the footage used, everything sounds just fine in PE itself.
The new computer is brand new, with barely anything installed except for PE9, Windows, VLC and Chrome. Is it possible the computer lacks the proper audio encoder(s)? I thought those would be installed with PE9...
So in short:
- old computer exports movies perfectly fine, but when I open my project PE9 exits immediately, due to not enough memory. I simply can't open my project anymore.
- new computer can handle the load, but produces noise or silence instead of the sound.
I exported two very short clips, one in MPG and one in MP4, the export settings are in the filenames. Both clips are the same content-wise and you should hear a bit of Johnny Cash as the soundtrack. But you won't.
http://dl.dropbox.com/u/4832845/HD%20720p%2030.mpg
http://dl.dropbox.com/u/4832845/iPod%20and%20iPhone%20-%20High%20Quality.mp4

Answer 1

Sorry, it's been a while since I had the time to dive into PE9 again. I updated the audio drivers and installed Service Pack 1 for Windows 7. That seemed to solve the problem briefly, because when I exported a short bit of the project, I had the correct sound. When I tried it again a while later, it was the old noise again. Very weird...
I continued my project in a new project (because the first one seems to be too much for PE9 to handle) and when I export bits of the new project, everything is fine. So it's probably a file used in the first project that causes the mayhem. Maybe one of the mp3's I'm using, although they're all self ripped from my own cd collection.
Still weird that it renders ALL of the sound useless when exporting. Also, PE9 doesn't indicate file problems (as I've seen in the past, with the little yellow danger triangle in the bottom left corner). I guess I'll have to split the project up in several smaller projects and see if I can isolate the troublemaker that way.
I didn't have the time yet to figure out the video codec used, but all footage is from the same camera and the mp3's used are self ripped. The computer has now been updated to the max.
I did however start the first project in PE8 and continued with PE9 later, when I moved to a new computer. But that shouldn't cause my audio to be messed up, should it? Using any of the standard presets results in noise or silence. I've tried them all
Also, when I export the new project (which was started in PE9), it exports to avi just fine. When I try avi in the first project (started in PE8, continued in PE9), I get the "unknown" error and exporting to avi or wmv is not possible.