Video freezes in XBMC Eden

Hello, for quite some time now i have this problem that the video freezes during playback, the problem is i cannot pinpoint why it is happening at is very random. It often happens when i start to play an episode f.ex. the video runs for 2 seconds then freezes, the sound continues to run though. I have no luck in quitting XBMC with the remote (im using the official IPAD app for that). XBMC runs on a windows 7 on a HTPC dedicated to just that. nothing new has been installed lately, nothing uninstalled. It was running fine for over a year now and suddenly started doing this. To quit i have to open the task manager and end the process and relaunch XBMC. sometimes (after relaunch) it works, sometimes not. sometimes it crashes when i download and add subtitles, sometimes not... it is so random that i cannot figure it out....

any ideas what i could try !?? or where the problem might come from ?
im glad for any advice !!

Thanks.