Video/pixel problems in windows HD5700

I do not really know what's wrong, it only began to appear by itself or when I watched the youtube video. When I stop playing, it happens with the whole screen becomes pixels. I have tried to reinstall windows vista and the same problem is found. it helped in the beginning when I uninstalled drivers and it was fine but when I tried today, the problem persisted.
I have tried all available drivers, and same problem
jag har haft kortet i ca 6 månader och det har fungerat fint tills föra vecka

my screen looks like this

Can you test with another monitor?
or can you test your monitor on another computer?

The fact that it happens after reinstall, seems to point toward a hardware problem

If you can Try with clean boot and in safe mode, does it happen?
http://support.microsoft.com/kb/929135

jag har försökt med clean boot som sa men problemet löstes inte. jag kommer att försöka med en gammal skärm som jag har i källaren senare idag. Det är konstigt för dom prickarna rör på sig hela tiden

I have tried with a clean boot as said but the problem was not solved. I will try with an old monitor that I have in the basement later today. It is strange for those spots are on the move all the time

I need the post to be in English and in addition thats the rule here.

OMG I'm sorry I was on another forum also

I have tried with a clean boot as said but the problem was not solved. It is strange for those spots are on the move all the time. I have also tested the old screen, but nothing helped. when I run the TV out problem pops up also.

I'll try to reinstall the old graphics card again and see if the problem is there

it works perfectly on my Radeon HD3450 I'm about to go crazy. And i dont haw another computer to test my HD57000

I think that you solved your own problem. It look like its the card; defective or incompatible.

yes but it has worked perfectly for about six months and suddenly stopped? after I installed the old video card, and once again the new, I have managed to make the picture look much better. I may just pixels problem when I play back the video now on youtube for example. I've tried to switch browsers, but it is the same. Could it have something to do with power? that it may be too little?

As you said in the previous post it works with one card but not the other
The card may have become defective
The associated driver may be causing the problem.

Go into your driver preferences and turn off anti alieas and all other options as this will aid in the diagnostics of the hardware.

I do agree with Rich but I always like to search for clues before writing off hardware.