Hey,
I closed the game earlier today and since then I cannot log into my world anymore. I really wish to continue playing. I've spent so much time proceeding this far. It would really stink to restart all over.
I had a similar problem and I followed advice somewhere in this thread to disable WAILA. I believe the reason was that if you logged out while looking at a Thaumcraft object, it would cause a crash when you logged in? In any case, I disabled it and could log in just fine. Then I enabled it again later and didn't have any further problems...although I haven't logged out staring at my research table again, just in case.
This is at least an easy thing to try.