Downloading a file from magnetmix is just a bit of a test, to see whether you have the same speed dropoffs as usual. Those files should download quite quickly. If the same thing happens, it can point to an ISP problem. What speeds did you get from magnetmix?

If your computer froze when your downloads restarted, perhaps you're trying to download too many files at once!

Mediacom were giving people trouble because of traffic shaping, I can only find articles from last year... they may or may not still be doing this? That would explain your speed drops but I can't be sure. Have you called them & asked if they're shaping bandwidth for p2p apps? Did you have the same thing happen when using Bearshare & Kazaa? Why not just fire up Bearshare & see if you still have the problem... that'll be a good test! Don't upgrade to Pro until this issue is resolved