I also get the 20100 all the time (with an USB Wifi thingy), no idea how to solve it, yet, though. The problem is probably the stupid university network. When I bridge the connection to the network, I think I get the 52100 and it's probably because the network only allows one MAC address and I have my usual card registered, not my USB Wifi thing. I'll probably try to register the other MAC address for testing but the problem is that my PC might not be able to go on the internet then for at least a day...
My DS also likes to kill the Windows explorer. Does this happen to anyone else and does anyone have an idea why it's happening?