Hey there, I need help badly!

I'm using a TBS 6980 dual tuner, with DVBLink TVSource & Network Pack v3.2 (+ OSCam + Jaycar reader...it's TVSource instead of DVBViewer cos I couldn't lock any channels in DVBViewer...long story, and because DVBLink have stopped selling that version or supporting DVBViewer), Windows Media Center (win7 ultimate x64), and 2x Linksys Media Center Extenders.  I've had problems pretty much forever, most of which have cleared up.  But something I haven't been able to sort out in all the months of trying, is DVBLink seems to drop one or both of the tuners randomly.  With TBS driver version 2.0.0.12, it mostly only happened when i accessed a tuner (live TV) on a second Media Center Extender (though also randomly after about a week).  There is no "no signal" message or anything...the screen is just black.  If a recording is scheduled it will sometimes come up with a "No Signal" error message, and won't record...but other times it will record, there'll just be nothing in it.

Originally (months ago) it seemed the problems were cos I didn't have Network Pack...so I purchased that too.  I think it ran a little more stable afterwards...but it still had these issues.  It's also why I upgraded to v3.2...but that hasn't helped.  Last week I upgraded to the latest TBS driver (v2.0.0.14), and then things got really bad!  It didn't only drop the tuner when I used the second extender...it happened all the time!  Pretty much daily I'd have to restart the computer and try and get it back.  So I've gone back to v2.0.0.12, but it's made no difference.  If anything it's worse still.  It's really not working at all.  I can reset the DVBLink service...doesn't fix it.  Restarting the PC usually does, but doesn't last long.

Please can someone help me?  I don't know if I need to buy a new and different tuner card or what.  But there's way too much money invested to turn around now.

Thanks heaps!