I have been experiencing exactly the same problems the last weeks.
When I installed my card, scanned channels on 3 satellites via Mediaportal TV server and DVB Dream, everything worked just fine.
Until I started to experience phenomena of channel "freezing" on Mediaportal (DVB dream still functioning OK), up to the point where I would get "no signal" on any satellite, whether I try with Mediaportal or DVB Dream.
After a while it dawned on me that the "no signal" problem appears after a number of sleep/wake cycles.
Only a reboot of my PC restores everything, but I keep getting the "channel freezing" on Mediaportal.
I get no errors in the log files, but I did notice that 2 events appear in the eventlog everytime I get a channel freeze :
- the error reporting service starts/stops
- the multimedia class scheduler service starts
I recently tried yet another software (ForTheRecord), but it suffers from the same problems.
Reading this thread however points me towards card or driver problems, since it seems to be DVBsoftware-independant.
I recently upgraded to driver version 188.8.131.52, but that didn't change anything.
Should I also try to revert to an older driver, as suggested in another thread http://www.buydvb.net/forum/viewtopic.php?f=21&t=179 ?
Thanks for any help,
P.S. I use Windows 7 64-bit