I have a HTPC running Vista Ultimate 32bit. I have installed a NOVA-T 500 card but am experiencing picture quality problems. They are difficult to explain, but basically there so far seem to be three types:

1) When viewing live TV, there is a constant interference 'sparkle' across the image. It is watchable, but annoying - its like some of the pixels are randomly flashing as red or blue.
2) Occasional interference 'boxes' accross the picture, again on live TV
3) When playing back some recorded tv, the picture suddenly had a stropng diagonal shape accross half the picture and the colours/contrast flashed wildly. When fast-forwarding or rewinding, the problem goes away, but when you play, the problem persists. When I rewind back to a portion of the programme that was OK before, the picture is garbled. Restarting Media Centre seems to solve the problem.

Sound is unaffected with all these issues. There doesn't appear to be any so-called 'stuttering' though with any of these problems - it is smooth.

I am running the latest drivers (MCE_CD_31H) and Vista is completely up-to-date. The machine spec is as follows:
Zalman HD135 case
Asus A8R-MVP
AMD 4400 X2 (939)
500GB Samsung Spinpoint hard disk
Nesteq Semi Fanless ASM PSU
Samsung Writemaster dvdrw
MSI ATI Fanless HD2400PRO graphics card
2GB RAM

The aerial is a good quality roof mounted affair, and has never given us any picture quality problems with the Topfield PVR (that this HTPC is replacing) or Sony Bravia TV inbuilt tuners. Picture quality is also perfect when running Vista normally to the same Sony Bravia tv, so it must be something spoecific to the NOVA-T 500

Any ideas on this?

Are you sure this is due to your Hauppauge card and not your video card?

Have you updated to the latest catalyst drivers?

I have a Nova T 500 in parallel with an ATI X1600 Pro. At first (very shortly after Vista was released) the picture was quite grainy and flesh tones not very well represented. After a few updates of both drivers and things are much better. However, I think the improvements I saw were more to do with the ATI/AMD drivers than Hauppauge's.

I will confirm the ATI drivers when I get home tonight, though I only built and installed the system 2 or 3 days ago and the drivers were downloaded then from the ATI site, so they are pretty much current.

When I view the normal Vista environment (web pages/outlook etc) through the same Bravia LCD TV, everything is fine. It is only using TV in VMC (live or recorded) that I get interference problems.

They should be fine then.

Your TV card is accepting a digital MPEG2 signal via freeview so the interferance must be coming from somewhere within your PC?  Maybe try switching it to another PCI slot?

Uninstall it first via device manager and then follow the Happauge instructions for how to clean up before a reinstall.

I had problems with every PCI TV card I tried. I had problems similar to yours, and also a much lower TV signal than when I used a Freeview box. I ended up trying a Freecom USB stick on a short (6") extension lead and it was much better. I then put this on a 1m USB extension lead and it was perfect. Not ideal as the encoding is done via software but it works for me. Everynow and then if my USB lead gets pushed close to the PC then the problems return. My case is a Antec Media case but this asldo happened when using the same hardware in a Desktop case.

This doesn't seem to be a widely documented problem to me. Most people have stuttering problems or basic tuning problems, but this type of interference goes largely unmentioned. Are we alone?  

Well, I think I've finally solved the problem myself with this. I decided to try a graphics card from my other machine and see if it made any difference - this was a last resort decision as the HD2400 had been purchased as it was specifically recommended for being a capable HTPC graphics card. The card I replaced it with is an MSI Nvidia 7900GS card which is also passively cooled. Installed all the latest drivers (after of course uninstalling all the ATI stuff) and hey presto, no more interference issues in VMC! Fantastic!

I can only guess that either the HD2400 isn't powerful enough from a performance point of view, or that the 7900GS with its own power connector straight from the PSU gives it a more stable power supply. Your guess is as good as mine, but the HD2400 is basically being binned. What a load of rubbish!

Now I am having to get a smaller quiet cooling unit for the 7900GS card as the MSI one is far to big and prevents me from being able to put the lid back on the Zalman 135B case!