This is the changelog between version .25 and .26, and
Siarhei Siamashka (the dev of maemo mplayer) reckons that he does not see what could cause this. Me neither, but I am no specialist.

The idea would be to compile several versions of mplayer, starting with half of the patches and see if there is a problem, i.e. by bisecting.

For those with more time than me, version .25 is revision 321 in SVN, version .26 is revision 335.