T60p + advanced dock + DVI KVM = FRUSTRATION!

[MountainMan]

i'm hoping somebody has some insight into the following problem:

i have T60p, an external 1600x1200 LCD, and an advanced dock. i want to use my internal and external LCDs simultaneously, in an extended-desktop arrangement. i am able to do this successfully, when the LCD is connected directly to the dock. however, when i insert a DVI KVM switch between the dock and the LCD, i can't get it to work.

when i try to switch to the 2-LCD "Extended Desktop" configuration using thinkvantage presentation director, i get the following error message: "The following settings you have selected cannot be applied properly. Change the setting and try again. Display Configuration"

neither the windows "display properties" panel nor the ATI catalyst control center fares any better.

interestingly, if i choose "Dual display: show same image on both devices", i can see the replicated display on both LCDs, at 1400x1050. however, as soon as i try to switch to "Extended desktop", the external LCD goes black, and i get the above-mentioned error message. i've tried setting the resolution of the external LCD to 1600x1200, 1400x1050, and 1024x768, but none of them worked.

since i can get it to work as a replicated dual display, the hardware is obviously capable to doing what i want. i assume the KVM is not correctly reporting the characteristics of the external LCD, so software refuses to go into the mode i want. i'm hoping there's a reasonable software work-around.

the KVM is an avocent 4SVDVI10 "Switchview Dvi 4 Port USB KVM Switch USB 2.0 Hub with Audio". it is designed to be able to display a 1600x1200 image, and a linux box on the same KVM is operating properly at 1600x1200.

the monitor is a dell 2000FP.

i'm only using the KVM to switch video; i don't have any USB or audio devices attached.

btw, i did try rebooting with the kvm switched to the T60p. it didn't help.

i'd really appreciate any insight anyone can offer...

[MountainMan]

new information: i just tried a borrowed gefen EXT-DVIKVM-241, and it worked perfectly!

i have one day left in my return period for the avocent unit. if a good work-around doesn't emerge, i'm going to RMA it and get a gefen.