Operating system is Windows 7 64 bit, drivers and progdvb are latest. The problem is, diseqc is always stuck to 1st input, works only sometimes. After many many restarts of computer and progdvb, it starts working, untill the next restart. I've tried various diseqc settings, such as delay time and command repeat - no luck. What can I do?

Try use ProgDVB x32.

ps: It is looks like hardware problem.

Yes I'm using x32 version, since x64 does not works at all - it fails at hardware initialization stage.

I thought it may be a hardware problem, but with standalone receiver, this diseqc switch works fine. I've tried to replace the switch - no difference.

That is not hardware problem with ProgDVB working over standalone receiver. But ProgDVB working over other device.