I have been reading up on previous posts similar to this one and did the same steps to fix this error. I started off by uninstalling and re-installing my tuner followed by updating my graphics card driver. I still get the following message:

"Video Error Files needed to display video are not installed or are not working correctly. Restart Windows Media Center or restart the computer."

 Just to make sure it wasn't my drivers I tried watching the high def channels on winTV 7 and it worked well. I run out of the HDMI port although I wouldn't think that would make a difference. I really hope someone can help. Below are my computer specs:

Windows 7 Home Premium

Processor: E6300 2.80GHz Pentium Dual Core

RAM: 2 GB DDR2

MOBO: Zotac GF9300-G-E

Tuner: Hauppaug WinTV-HVR-2250

This happens to me also requently, but usually it disappears after a few attempts to view live tv or  aparticular dvd. Sometimes I have to restart the PC.Have no clue why, I had the same problem on Vista.

Im using a floppydtv as tuner, ati 3200 HD as gfx chip. 32 bits version of win7 OS

/Henrik

Over on the Silicondust forums, ISTR this being blamed on HDMI audio drivers. I use S/PDIF, and I can recall seeing it once. I never found out why.

 I have recently had  to wipe my hard drive clean and took the opportunity to update to Windows 7 professional ever since which I have been receiving the message that files needed to display video are not installed etc.at first all I needed to do was restart Windows Medium Center or restart the computer but now even if I do this it refuses to open.

As a comparative novice to computing and pensioner to boot can someone explain in every day language what I need to check or do to rectify this matter

 I have Intel R Pentium R 4 CPU 3.06 GHZ 3.06 GHZ 32 Bit operating system

Are you using HDMI for audio? If so, these threads may help:

TGB

avsforum.com