Horrible movie/player/windows lags when watching movie over 20 min??

[1337inside]

Hi, i go BS Player Pro version 2.57 atm and lately when i run a movie i get horrible lags with player, movie and windows, also player crashes every 30 minutes or so, it doesn't give me an error message that it crashed i only hear weird sounds and also hardly open taskmgr because player use my cpu at 100%...

I have win 7 ultimate x64, i didn't had problems never before, it started lately when i got new graphic card, it is AMD Radeon HD 6850, all other players work fine, my motherboard is ASUS P5B Deluxe, i have 4 gigs of rams and cpu with 2 cores at 3.0ghz

Codes i use are only those ones installed with BS Player when i installed player, i didn't install any other codecs, i did same thing before many times and never had such lags, i tried changing rendering modes to few and problem always exists... i don't know what to do anymore

I also tried re-registering quartz.dll but that didn't help at all, anyone have any ideas?

Thanks