freezing of dvd picture

[tarlach]

i use ravisent cinemaster to play films on dvd. when i load up the programme and select play the dvvd control panel disappears, and the only way to stop the film is by switching off the computer or using ctrl alt del (twice) the end task utility will not work either (at least not within 30 seconds).
anybosy have any idea as to how the problem can be solved?
thanks slainte tarlach