I doubt reformatting everything would help. This seems like a hardware issue. A couple of things you can try are try connecting through another mode (dialup, maybe) and see if files get corrupted. That way you can diagnose the problem and identify if it's a software problem or a hardware problem. I have a sneaky feeling it's something to do with your router, but if you could get some more diagnostic information such as using a different means of connection (maybe even a different router, or wireless or something) that would be great.
Good luck.
I just saw your other thread--the one where you are not able to connect to LAN. How were you able to get around this? Possibly there's a connection between that problem and its subsequent solution and this problem?