After jailbreaking I had a hell of a time getting Cydia to do anything useful. It must have crashed a couple dozen times while trying to get 3G Unrestrictor. Once in a while it looked like it was getting close, however, so I kept trying and eventually I must have hit the magic combination. It came up and ran perfectly, I was able to buy and install the app and everything works just fine. Now again today it was back to it's usual non-functional self but once again, it did run once which was enough to get a couple other small utilities installed. Persistence and patience. I get a lot of server not available or found messages so I tend to think it's somewhat unstable software driven over the edge by an unstable or heavily used server.