vBulletin settings on this forum sends a pre-made password with upper and lower case letters and numbers.
Caps or not, i have copied the text and written it manually, dosen't work.
Please, can you just do a manual reset by admincp?
Or can you check if there is another member with same username or memberid "Matteo"? Maybe thats the problem.
Edit: ..Oh lawd, i can see there another member at this forum with same username. That will freak out VB.
Cannot view profile because i don't know his member id.
Forwarded the issue with 2 account names to Bossland. That happens when you register a forum name, then a shop name (the shop auto-creates a forum name).