Precision M4600—Suddenly Can't Extend Display to Third Monitor

Setup:

Precision M4600 with NVIDIA Quadro 2000M

Docked to Dell E-Port Replicator. Lid closed.

Windows 7 Enterprise

Dock ports and their monitor connections:

DVI --> Dell ST2220T

VGA --> Dell 1909W

Display Port ---Via DP-->VGA Adapter-->Dell E198WFP

I have been running this setup sucessfully and with absolutely no problems for about three months. Every now and then, after the M4600 had been in hibernation overnight and I'd come in and dock it in the morning, I would have to go the Screen Resolution control panel, click on the E198WFP monitor, and re-extend desktop to that display, and then it would be fine for a while.

Yesterday I worked at home and just had a single out via HDMI to a Dell ST2220T monitor, as I do very often. I disconnected the monitor and closed the lid (the sequence of those two actions being inconsistent) several times to work from different locations. One of the times that I reconnected the monitor and opened the lid to bring it out of sleep, the resolution was incorrect and the image was distorted. I restarted the system just to give it a fresh reset. This is the first and only anomoly I have experienced with this sytem regarding the displays.

This morning, I cam it to work, docked my system, brought it out of hibernation, and suddenly I am unable to extend my display to a third monitor. I can only display on two of them. Even the NVIDIA control panel is now saying that it only supports two monitors but I know it should be able to do more than that and I have been doing so for a while. Optimus is not an option for me because my monitors are different and have different resolutions.

I scanned for hardware changes and got nothing.

Any ideas?

Thanks you.