This question already has an answer here:
I have had bitcoin for a little bit now. It has been going very smoothly. I have set up 3 accounts for various activities, privacy, and security reasons. I now can not get all of the block chain. When I go to download more of the block chain it just sits at 175408. I have been at it for hours. When I first got bitcoin it worked perfectly, but now even after reinstalling the bas** it is still stuck there, and my total connections went from eight to a one. If anybody has any suggestions on to what the problem could be I would be grateful.