A strange one for you MC Experts (memory change broke live tv)

Hi

So I have had a media center system for a few years, it ran XP, then Vista and now Windows 7 x64.

I have a strange issue happening:

1. The system kept getting blue screen of death
2. I traced this to the memory and changed it for some other sticks – still 2GB (was 4 x 0.5 GB, now is 1 x 1GB + 2 x 512 GB)
3. No blue screen of death since – problem solved, but…
4. Watching live tv now doesn’t work, it breaks up and is un watchable, but…
5. On the xbox 360 Extender I have tv quality is excellent, so…
6. Must it be a graphics card issue conflict with the new memory???

Any help or suggestions very welcome…

Thanks Mike