My videos will not play,only sound

[Rapidrob]

I have a strange problem. I use an older computer that I have upgraded to store all of my videos. All are played with VLC as per Linux Lite software.
If I open any of my MP4 videos,the first frame is shown and never plays any moving video images.The first frame stays on and the audio plays in a normal manner. Any of my videos will play on my other LL OS computers with no issues.
This computer does not have a built in video port, the output is on the GeForce card. Nothing in BIOS shows a selection for graphic outputs. Resetting BIOS does not help. MB has latest drivers/firmware.
Any video on Youtube plays just fine.
Linux Lite 4.8
CPU Q9650 @ 3.00 Ghz
Gigibyte P35-DS3L motherboard
GeForce GT9800 graphics card running 340.108 Tested drivers
500 GB HDD

[Jacob Pertou]

Have you tried changing the settings under Tools - Preferences  - Video - Output?

[Rapidrob]

A 4 GB DDR3 memory stick would fail after one hour and cause some strange things to happen. Firefox would crash after two minutes and the mouse would lock up. The other memory would try to run the OS but was overwhelmed.
Using MemTest86 it took a long time to error out after being cooled down.