Like for bug #458, I'm using two screens with different resolution, but with Debian Linux. Workrave worked very well for a while, then I started fiddling with the status window options.
Now when I run workrave a very little white window flashes up for less than a second and then disappears. The program don't crashes but runs without any window. Purging it conf files and reinstalling the prog didn't helped.

My system configuration is:
Debian   Unstable
xorg     7.1.0-12   
xfce4    4.3.99.2
workrave 1.8.3-1

...anyway, thanks you a lot for Workrave! :)

I'm getting similar results.  I'm running Ubuntu 7.10, and X in Twinview mode
using two monitors of different resolutions.  The first time I ran Workrave,
I could see the small usage window - with time remaining before the next breaks.  There was no workrave item in the panel, and no visible way to get to the configuration window.  I closed it, and tried to start it again from the command line, but it said it was already running.  So I killed it with "kill", and ran it again from the commandline.  This time I saw a small black-outline rectangle animate itself closing or hiding onto the panel - except it does not actually appear in the panel.  It's running in the background, though, but there's no way for me to configure it to my RSI needs.

I'll attach my xorg.conf file in case that helps.

Linux: 1.8.4-2ubuntu1
Gnome: 2.2
Xorg:  1:7.2-5ubuntu1
nvidia-kernel-common:    20051028+1ubuntu7

Created attachment 123
My xorg.conf file for Twinview (one big desktop spread across 2 monitors)

This is Luke Kendall's xorg.conf file.

I think this bug was fixed some time ago. I added some sanity checks to make sure that the main window always remains visible.

The "NoTwinViewXineramaInfo" could be the cause of this problem.

Please reopen if the bug is still present in a more recent version of Workrave.