I'm not able to submit a question using Opera 10.10 on Windows XP SP3. I was logged in, every field was filled etc. No error messages were shown. After clicking the submit button, nothing happens.
After this I opened FF3, logged in to the site, copy-pasted all the form fields from Opera to FF, and clicked submit. This was successful.
It seems to me that the "Ask a question" page's javascript doesn't support Opera. Please fix this. Opera is the only browser that rocks.
(And now I just discovered that meta.stackoverflow.com has the same problem, as submitting this question with Opera was not possible and I had to do it with FF3)