external monitor and tv doesnt display movies.

help.

trying to get my laptop to display films on either tv via RCA socket or external monitor . trouble is that all i get is a black display in whatever player i use . I can see desktop and player skin fine on all displays and film shows fine on lcd display of laptop.
specs . pentium mobile 500mhz processor
ATI 3D RAGE LT PRO.

Tried all different resolutions and colour quality.
Tried media player , Bs Player , ATI video player

Have managed to get video to play on a couple of occasions on external monitor by altering screen resolution but as soon as you close player down and restart it again its back to black screen .

Any Ideas would be greatly appreciated.