Help! Strange text in subtitles

I've switched all my macs and my atv to frodo and now i've noticed a problem with the subtitles.

A lot of random letters are mixer with the right text of the sub (text of the sub f,kjsrhiu fa,khg fa{}{{{ !! ? sh> djs)
and make the subtitle unreadable.

I did not have the problem with eden.
I'm having it on 3 different macs and the only thing i've changed is the version of xbmc.
If i try on vlc or quicktime everything is ok,

I always use handbrake to make my atv-mac-optimized h264 and before eden i remember that there was a problem with subtitles not showing if embedded with handbrake.... but with eden it was solved and everything was ok.
Now, the subtitles tracks are there, but they all shows with a lot of random added letters..... seems something like wrong charset os something like that.
When i open the original mkv, handbrake says "utf-8" subtitles. If i re-open the handbrake-encoded-m4v the subtitles track is shown as TX3G.

I'm trying to re-encode a new file with an older version of xbmc (0.96) to see if there is any difference but with eden i've used 0.98 for months without problems, so i think the problem is not in handbrale version.

any suggestion?
thank you