flickering screen

[Embarq Customer]

Dear All,
I have a flickering screen when I play back videos on both VLC and Movie player.
I have switched off the desktop effects following a suggestion on this forum. (I can't remember who suggested it, but thanks for the tip.)
I downloaded Gnome last week to see if the problem would occur in a different environment. The screen flickers at about the same rate.
Does anyone have any further ideas?
I use a nvidea ATI 1300 radeon graphics card, I would be willing to pull it out if it will stop the flickering.
Thanks in advance.

Kevin Jones