I can't sync the wallet, it always exits with an "Unknown Error". Any advice?
I deleted the data folder, tried again multiple times.
Recently it got past block 50000 but then the error occured again.

I was having similar issues with the downloaded wallet. Then I copied my json file out of the %appdata% folder. Then used that to login to
https://dbix.io/. Worked like a charm and a familiar interface to myetherwallet. Try that as it works for me. Unless you insist on running a node.