Special characters on thread titles gone after upgrade

[tidesson]

Hello I'm a VB newbie with a small problem. I was using vb version 4.0.8 and recently upgraded it to 4.1.2. To do this, I created a new database and backed up there all the content of my forum before doing the upgrade in case anything went wrong. The upgrade to 4.1.2 in this mirror of my forum went OK, didn't give me any kind of errors, and the forum worked fine. However I realized soon afterwards that the special characters on the thread title links were gone. I'm spanish and I'm using vbulletin with a spanish language pack; there's a lot of thread titles with 'special' characters like 'ñ', or 'á', 'é', 'í', 'ó', 'ú'. Those letters are not showing properly anymore. One quick example:

thread titled "Enredados BSO Español"

is showing as "Enredados BSO Español"

This only happens in the thread titles and not anywhere else in the whole forum, at least not that I know of. I've been looking around but can't find a solution for this. I could go and manually edit all the thread titles, but there's a lot and I want to know whats the cause of this and if there's any quick fix for this issue.

Thank you in advance