On the ECB mailing list somebody asked the following question:

>> For several weeks now, I'm getting emacs cvs to stall when editing
>> Python files. I'm using cedet 1.0 beta2b ( through ECB ). And *Messages*
>> says something like:
>> wisent-parse-stream: Invalid start symbol bovine-inner-scope [29790 times]
>> Any hints fixing this would be appreciated ( I can still C-g out of it,
>> but it's a pita )
>> TTimo

I have had the same problem with regular (as in "released") versions of ECB and Python files. As soon as I commented out the line

(setq semantic-load-turn-useful-things-on t)

in my .emacs file (needed by semantic for, among others, Intellisense), the problem disappeared. Your mileage may vary, but it worked for me.

With kind regards,