I did a fresh install of WP2.6 and ran into a few problems, I already mentioned them in the feedback forum (topics 190865 and 190951)
But after these were solved, I had a problem changing passwords, it might be it only happens after SUBMIT when the two passwiords do not match. I could no longer log in: neither password was accepted.
A next time I requested a new password, I got it and I could login. Having retried, I checked the passowrd being changed after retry a login. It was - and much to my surprise, I could login using the new password....
On the failed attempts, the log shows the reason of the non-compliance:
This "X-Powered-B" is the big problem. It should not be mentioned (Apache has a habit of being tolerant to non-colmpliance, but my server is very strict).
I tried to find out what caused this string, but couldn't locate it anywhere in the code.