500 Error returned, yet Rails log says everything is ok

Hi, I moved my first Rails app from local dev to hosted env yesterday.
The basic pages work ok. I am using Rails 1.2 (located in my app's
vendor dir). I am using the Ajax Scaffold. These pages work ok.
However, when I have my Firefox Greasemonkey user script make an XHR
request I encounter a problem. The request is handled by the Rails app.
The Rails log (i'm running in Dev mode at this point), says everything
is fine.

Rendering url_votes/vote_summary.rxml
Completed in 0.09432 (10 reqs/sec) | Rendering: 0.01089 (11%) | DB:
0.01917 (20%) | 200 OK

However, the client recieves the Error 500 Internal Server Error - App
Failed to Start Properly message.

This same scenario works fine on my laptop env. Any suggestions how to
debug this problem further?

Same thing for me, and i'm still stuck .

Any news?