Problem driving dual external displays on wakeup

I posted the following here back in February and it was archived without resolution (one other subscriber noted having this problem too). Still having this difficulty so I'm reposting ...
I am having occasional irregularities with my Mac re-driving a dual-display setup either waking from sleep or after a normal energy-saving screen shutdown.
The setup: a new MacBook Pro 15" with Snow Leopard. Normally I work with the cover closed using two Acer external monitors, both connected via DVI. The main monitor (H - arranged horizontally) is connected via the Apple mini-to-DVI adapter. The secondary monitor (V - arranged vertically) is connected via an Iogear USB 2.0 External DVI Video Card, attached to the machine via a Belkin USB hub.
The problem: sometimes when I wake the machine, or come back to it after the monitors have been powered down, the H screen will present nothing but snow - a complete black-and-white pixelation effect. Sometimes this will stop and the login prompt appears and all is normal. More often I have to wait for the monitors to power down again, then try to wake them. Sometimes this clears it, other times not. In the worst case I can not get the monitors redriven and have to open the machine and effect a restart.
I have also noticed at times that the Mac seems to forget about one or the other monitor, driving just one and moving all the windows over to it. Again, have to restart to bring everything back in line.
Sometimes I can go weeks without this occurring, and other times it will happen nearly every time.
The Mac OSX software is up to date and as far as I can tell I have the latest Iogear driver (although it's not the Iogear-attached monitor that pixelates).
Any thoughts on what might be wrong, or what steps I can take to diagnose the problem?

This question was never really answered but I reposted it since it was moved to archive.

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