AverTV Express Mini trouble tuning some hd clearqam channels

[BerMM]

I just picked up a refurbished AverTV Express Mini and I'm having trouble tuning clearqam hd channels. The problem varies from A/V sync to breakup and loss of signal altogether. I would suspect signal problems, however I have other tuners working just fine off of the same splitter. I'm going to try switching cables and splitter outputs and will report back.

FYI, the system this is in is a Dell Inspiron 9400 with 2ghz core 2 duo (T7200), geforce go 7900 gs, 2gb ddr2 800 cas4, sata 320gb seagate 7200.4, and Win 7 home premium 64 bit output to a samsung p2370hd @ 1080p via dsub.

Thanks!

edit:
I tried different cables and splitter outputs but I'm still having the same problems with certain hd channels (4.x, 5.x, 9.x have issues, while 7.x and 13.x do not). The p2370hd has no problems with any of those channels when its tuner is directly connected to the same cable. Is this a sign that the AverTV is defective?

Another question: This has an FM tuner, but it uses the same input as the clearqam tuner. Is there some sort of combiner that can add the signal from a FM antenna to the clearqam input without the fm feeding back to the cable company?

edit2:
I've done some googling and it looks like I'm a victim of clearqam channel remapping. It's been forever since I used the tuner on the p2370hd and it too was having trouble with some channels that should have come in fine (though not the same ones as the AverTV). I resolved that problem by rescanning the channels, but naturally WMC isn't so simple. Any tips on discovering what the mappings should be?

edit3:
I hooked up my desktop WMC (WinTV-HVR-2250) in place of the AverTV and it reports 100% signal on these channels, so I've submitted a ticket to Avermedia and will hopefully have an RMA soon.