Bitcoin Block Download frozen
Lets start with the version of the bitcoin wallet that you are running. Are you running the latest version 0.6.3?
Second, which OS are you using, It'll help us to tell you which files to delete in order to restart the chain download. 

Delete the blockchain data and reload the chain.  !!! Do not delete the files wallet.dat, addr.dat and bitcoin.conf. Except for those, stop the wallet, delete all other files, restart the wallet.

The files you'll see and that you can delete are, e.g. blk0001.dat, blk0002.dat, blkindex.dat, *.log, peers.dat, the whole subdirectory 'database'