I have the same problem. Tried all this and my PC still BSOD when both cams are running. Either party can run a cam alone reliably, but when both are connected my PC bluescreens immediately. Running a Toshiba notebook with a Logitech quick cam. No change to the drivers. Just started doing this magically a few weeks ago. Any ideas?
Stuart

Sounds like the software is looking at a video card
Re-check your settings

Test your webcam here to make sure it broadcasts ok - Hit 'Allow' in the top window and check your cam in the left hand panel.

http://www.testmycam.com/

working OK ?

CONFIGURE TO SKYPE
Connect webcam
Its good practice to disconnect and re-connect your webcam before you start (To reboot the webcam software) - if you have been using it elsewhere the SKYPE software may have difficulty in locating it, even if you exited the previous program correctly.
The reason being, the webcam software can remain hooked-up to a program and needs to be rebooted.
Mine, I just unplug it from the USB and plug it back in to reboot the software.
If yours is integral with the computer you will have to re-start the computer, use a keyboard shortcut or disable / enable the webcam from the Device Manager.

Start Skype.
On the 'Tools' menu, click 'Options'.
In the navigation pane of the Skype 'Options' window, click 'Audio Settings'
Run down the list setting your defaults
Select your webcam as the default microphone.
Make a free test call
Click 'Save'
In the navigation pane of the Skype Options window, click Video Settings.
This will launch your webcam
Adjust quality of picture in 'Settings'
Check the correct webcam is shown as default
Click Save
Test your webcam by making a Skype test call.
For more information about how to configure Skype Messenger, please visit the following Skype Web site:
http://support.skype.com (http://support.skype.com)