I also tried EVERYTHING to fix this problem. The only that really worked was to upgrade to Lightroom 3.5 (I had the 3.3 version) and now it works beautiful! Hope this helps.
Have LR 3.6 and have been getting the same error for the past two days. I have removed authorization from both LR and FB. Reauthorization was no help.
Anyone know the link of where to submit bug reports?