Dell XPS Studio i7 problem resuming from S3 sleep

I like to put my new XPS Studio i7 into S3 suspend mode when I am away. This works properly if the suspend time is of relatively short duration (< 4 hrs). For longer durations, when I press a key to resume I can hear the computer respond (fan revs, etc.) but both of my dual monitors remain black. I have the most recent drivers and bios. I've seen various posts that indicate this could be a vista problem, or a graphic card problem, but no real solutions that have worked for me. How can I best troubleshoot this?

What I've Tried
Tried the various power management settings from performance to energy saving
When resumed with black screens, I plugged Wacom tablet into USB hoping it would trigger a video update

My Configuration
Dell XPS Studio i7 940
ATI 4850 graphic card
Dell 2408WFP primary monitor
Samsung SyncMaster 912n secondary monitor
Dell supplied USB mouse
MS USB Digital Media Pro keyboard
Vista Home Premium 64 bit

Also, I am using an IOGear USB KVM switch that switches the USB Keyboard, mouse and 2408 display between the i7 and an older Dell laptop. The laptop suspends and resumes properly.

I found this in another forum and it worked for me. In Device Manager, Network Adapter power management tab I unchecked the "Wake on Link" option. I am now able to restore from S3 without problem.

Jerry