I am having the same problem. The only thing different I did prior to the problem was I changed to permalinks. However, even after reverting this change, I am still having the problem. The feed is fine – Facebook can pick it up when I enter the direct feed URL (instead of the feedburner URL).
Every attempt at “Resync” ends up with a time out error. The feed validates fine.
And what is even more odd, there is no record of the Feedfetcher bot in my access_log – however, on another blog on the same server, “Resyncing” is fine – no timeout – and the bot is seen in the log.
I’m stumped.