Nether will not load.

When I try and enter the nether the game seems to freeze up at building terrain.  After about a minute or so you can for a split second hear the nether and then game crashes.  Nether was working fine the other day.  I have uninstalled and reinstalled.  I've also had a friend join the game and see if it worked for him and it didn't either.  Please help.  I don't want to have to restart.