So I've had this problem twice now, the first time was an easy delete MineCraft folder fix...the second time was a little bit more. I had to contact someone who knew a little bit about the MineCraft code and here is the fix for now until it changes or Notch fixes it.
1: Delete MineCraft Folder *as always*
2: Clear Cookies and History *i tried it without and it didn't fix until i did this*
3: Restart *it may not be needed but better safe then frustrated*
4: Open your browser go to the MineCraft website.
5: Use the in browser game client, log with that client into the server and move a couple of blocks
6: Tada! All fixed. The online client forces a block over-write..and a certain block is what is causing the issue for it to not load and therefore crash.
Well I hope this helps some of you and if not please post your problem here and I will try to help.
1: Delete MineCraft Folder *as always*
2: Clear Cookies and History *i tried it without and it didn't fix until i did this*
3: Restart *it may not be needed but better safe then frustrated*
4: Open your browser go to the MineCraft website.
5: Use the in browser game client, log with that client into the server and move a couple of blocks
6: Tada! All fixed. The online client forces a block over-write..and a certain block is what is causing the issue for it to not load and therefore crash.
Well I hope this helps some of you and if not please post your problem here and I will try to help.