My ipod touch (just updated to IOS4) will not appear in itunes?

I just updated to IOS4 and my ipod touch will not show up in itunes. I've already tried restoring and erasing all content. When erased all content, it started a never ending cycle of restoring, which I fixed by using a different computer. When I plugged it into the other computer it synced fine and showed up in itunes. For my personal computer though, it will not show up. I've been using that computer in conjunction with my ipod for about half a year now, so I don't know why it would just stop working. What could I do to fix this problem?