ITunes on iMac imports CDs slow and eventually stops

Question

I have 2 iMacs and one Macbook. Both iMacs are Snow Leopard, the Macbook is just Leopard. Only one of the iMacs has this problem. I'm running the latest iTunes and I take in all Apple supplied updates every week.
This problem existed on the previous version of iTunes (9) and it did not get better after upgrading to version 10.
There are actually several problems, and they are quite bizarre. No other posting in the Forums seems to cover them.
1) When I import a CD, it starts out OK. Kind of slow, like 3x, 4x but it moves for a song or two. Then the import progress bar stops updating. It seems to freeze. If you touch the mouse, the bar jumps way ahead, or even to the next song. Then it just sits there again. If you move the mouse continuously you can eventually get the thing up to 6x or 8x and it will finish. If you don't move the mouse, it eventually just goes to sleep and never finishes. There is a workaround for this - if you play a song from your library while you are importing the CD then it will eventually finish. The progress bar retains its weird non-linear behavior, but it will finish and eject the CD. It never gets faster than about 8x and my other iMac can import at about 20x.
2) Sometimes when I start playing a song from my library (not importing a CD at this time) the progress bar jumps all over the place. It will be 30 seconds into a song and then it flashes back to 2 seconds, then ahead to 32, then back, etc. The audio during this time is fine it does not actually rewind the music.
3) I also have an Airport Express. When I set this machine up to play through the AE it will play OK for 10 or 15 minutes. Then it will just stop. You cannot click anything to make it responsive. You have to right-click on the iTunes icon and do a force quit. Other machines in the house can play through the AE for hours with no dropouts. There is good network connectivity, the machines are only 15 feet apart.
If the problem was just the importing of CDs, it might seem like a hardware problem. But I have these other 2 problems and they have nothing to do with the CD. The only constant is iTunes. The rest of the apps on the box Mail, Safari, Firefox, etc. seem fine. There are no glitches in them.
Should I reload iTunes completely ? If I do that will my library be lost ?
Theoretically I do have a saved copy of the library in my Time Capsule.

Answer 1

This was resolved with a hardware repair. The USB port was shorted causing an interrupt storm and affected iTunes.