To track the problem down, you can try this:
(setq max-specpdl-size 5) ; default is 1000, reduce the backtrace level
(setq debug-on-error t) ; now you should get a backtrace
C-h a ; in speedbar
You should get a backtrace upon the error, and at that point, you can track down the offending routine.
I’d also try loading emacs w/out your configuration file (emacs -q), to see if there’s something in your .emacs that is affecting things. (I don’t get the infinite loop using C-h a). And if it is your .emacs, then the best way I’ve found to track that down is either binary search (put an error (error "frog") or somesuch in the middle of your .emacs, load, test, if no problems, put the error at 3/4, otherwise at 1/4, repeat…), or manually evaluate your .emacs line by line (region by region), testing after each portion. Those settings should help.