Windows 7 - two DVB-T tuners not working together

with windows update 28. dec 2011 my two tuners suddenly didn't work. They work one at a time, when I just select one of them when searching for channels- WMC sees both tuners, but if both are selected no channels are found.

Both tuner have been working together for more than a year, and they still work in the DVBViewer demo version.

I use 64 bit Windows 7. I have tried to go back too a point in time where it worked, but with no luck.

Bad luck. It looks like it's only me who have this problem.
The tuners are USB, but they have been working fine untill this update.

A windows update some time ago disabled DVD playback. A bit annoying that these updates mess up things like that.