I'm not sure if this is actually a Linux problem, and it might turn out to be a Windows issue -- but here it goes anyways.

Description / Context

My setup: 2x21" wide-screen monitors, each with a resolution of 1680x1050. This totals to 3528000 pixels.

I'm remote desktop'ing to WinXP PC. Although this is irrelevant, it also has 2x monitors, each with a resolution of 1280x1024. This totals to 2621440 pixels.

FYI: As per Remote Desktop Connection (Terminal Services Client 6.0), there is a limitation of the remote windows machine such that the total pixel size must not exceed 4096 x 2048 = 8388608 pixels. As you can compare, the console pixel size, and even my 2x wide screen does not exceed this limitation, so we can safely say that this isn't the problem.

How I Remote Desktop (and it works)

I remote desktop using "rdesktop", using the "span" protocol of RDP. (Details here: Using Remote Desktop with Dual Monitors | SplitView)

To do this with rdesktop, I use the following command:
rdesktop -u username -d DOMAIN -z -x -P -f -a 16 -g 100% -0 my-pc-name
This basically creates a remote desktop session with the target PC, using 100% of my client resolution (1680x1050x2), 16-bit colour, spanned across both monitors. Usually, this works well!

The Problem:

However, sometimes, when I go to connect, here's what happens.
0. The rdesktop window opens, and the remote session is initiated.
1. Prompted with the username/password prompt in Windows.
2. I enter my credentials, and login.
... * ... where normally the system would login, it hangs here. The login prompt is "grayed out" (as though it's processing the credentials?), but nothing happens. After about a minute, the connection disconnects, and rdesktop closes without any return message.

I can try again as many times as I like, and it just does the same thing.

The Workaround

Now, if I try a lower resolution, then I can get in. i.e. if I use the param:
-g 1024x768
for example, in almost all scenarios, this works (once I've had to go as low as 800x600 though...). Once I'm in there, then I can close all programs, reboot, and then I'll be able to RDP once more at full resolution, but this is terribly inconvenient.

How To Fix?

Any thoughts on what the problem is here? It's probably a problem on the remote windows machine, not being able to resize it's resolution to the requested 1680x1050x2 ... but I'm at a loss as to why, or how to troubleshoot diagnose.

Does anyone have any experience with this?

Thanks in advance,