looks like your problem...seems like a network/server setup issue. good stuff in there

All right, try this.

Next time your computer has reached the "cannot right-click" stage, close every application.
Then Ctrl + Shift + Esc to open the Task Manager.
Go to the Processes tab, and look for any residual firefox.exe or iexplorer.exe processes still running.
Kill them.

Firefox has the option to control almost all java behaviour on the advanced java properties of the content tab of the Options (Tools / Options).
Uncheck "move or resize windows" and "raise or lower windows".

The Twinview menu options of the Nividia contol panel have a toggle (check box) to "prevent windows from opening off screen". Make sure that is checked.

Have you tried using 2 nVidia cards or 2 ATi cards instead of one of each?

It's not firefox.exe processes, that was one of the first things I checked for.

Although at times i'm unable to access the task manager but the times I am able to, there is nothing unusual there.

I have that box checked.

I haven't tried using two of the same cards - but atm i've removed my ATI card and the problem is still there.

Hi GodlikeRoy,
Sorry I don't know the fix - but it does seem software-related as you had earlier surmised. You had mentioned getting the event log regarding "The browser service has failed to retrieve the backup list too many times on transport \Device\NetBTTcpip" with a slew of numbers thereafter.
Looks like really long string of numbers (6C607F20 - C2A0 - 448C -AC17 - 553706A2AD43 in your case) is just the physical address of the specific (network/video) adapter and it's guid (identifier information given by OS or an application). At least it points the way to what failed to provide the 'highway' for the information requested by the browser service.
The 'browser service' the error is talking about is the "Computer Browser Service" (article at: http://support.microsoft.com/kb/188001).
Articles note this stuff happens more often with multi-homed setups (where there is more than one network/video adapter present, multiple setups etc). You had already noted this in your original post when you mentioned the 4-monitor setup.

The Computer Browser Service (it's called Active Directory in XP) is supposed to do two jobs:
1. maintains an updated list of computers on the network ---> error shows it "failed to retrieve the backup list too many times" using the network adapter though.
2. and also supplies this list to computers.
It is supposed to do these two things on a per-transport basis (transport = every time the actual physical network card bound to NetBT TCPIP is utilized).

Articles online talk about the failure of this causing freezing, lagging, unexpected non-function...and etc that you had already mentioned.

Sorry, I don't have any fix - just enough digging to find out it is a communication difficulty related to Active Directory sputtering because it can't do its job right using the NIC and its protocol right now. Good night.

Okay,
Before we try replacing the network card, or adding a PCI card if onboard, try rebuilding the TCP/IP stack:
In Windows XP, how do I reinstall TCP/IP?

Thanks for the info kartaska igra.

Low Dough - I just did that, i'll play around for 10 minutes or so to see if it helped or not.