Guys I "had" the same exact issue last night with my Dell XPS 420 dual cable card setup. All channels showed the RC-BSOD (Restriced Content - Blue Screen of Death) after 2pm CST.
Manually updated (not via windows update) to the 1.17 firmware Monday, May 12th. Tuners working fine until yesterday.
Steps I took to troubleshoot.
1. System restored back a day, as I just installed the latest rev of My Movies, iTunes, and PowerDVD 8. Did not fix the issue.
2. Then I wondered if my default MPEG2 audio and video codecs got fubar'd, as I once read that if a codec pak or something changes the default MPEG2 decoder from Microsofts to something else it breaks the DRM path. Downloaded vmcd.exe and found that everything was still set to the MS codecs.
3. Started thinking the HDCP was the culprit, and maybe my tv or video card wasn't interpreting HDCP properly. If this was the case, all my extenders should still be working, annnnnnd they weren't.... wrong again.
4. Started cursing DRM, Microsoft, Comcast, and shitty broadcast flags....
5. Reset power to my cablecard tuners.
6. Reseated my cablecards in the tuners with the system on.
7. Checked into the troubleshooting faq on this Microsoft page. http://www.microsoft.com/windows/products/winfamily/mediacenter/cablecard.mspx Make sure to expand the Cablecard Troubleshooting section.
8. Looked at the Cablecard activation pages in the media center interface and saw some messages stating to call the cable compcany.
8. Called my cable provider, and had them send an INIT signal then a HIT signal 5 minuites after.
10 minuites later everything was functioning again....
Thats my story... hopefully it helps....
My thinking is the windows update version of the firmware update came down and fubar'd the cards since they were already at 1.17, or not.....
Angeloooo