Fill up all the drive space on Windows 2003's Boot volume (typically C:\) and you could be in for a big surprise: nothing, or more accurately, no video display other than a black background, maybe the part of the Windows logo, and a few icons.  This very well may be lucky enough to be prefaced with a normal video display while Windows notifies you on logon that the it is unable to load your local profile before your desktop eventually loads and things fade to black.

You're a savvy admin and have no troubles accessing the server remotely and doing an emergency clean up of the volume, thus ensuring Windows returns to normal operations.  But go back to the server: black screen.  Reboot for good measure: black screen.  Corrupt OS? A dreaded Microsoft Tech Support phone call?  Maybe, but you could be looking at nothing more than a messed up color scheme.

Put those admin skills back in to action and do some investigation and possible remediation of your server's registry - remotely.

1. If possible, log on to a functional Windows 2003 server and open the registry (regedit.exe is best for this task)
2. From the File menu, select "Connect Network Registry..." and when prompted, enter the computer name of the affected server.  Upon successful connection, you will see all five hives from your local computer, and the HKEY_LOCAL_MACHINE and HKEY_USERS key from the remote computer.
3. On the remote computer, expand / navigate to:
   HKEY_USERS\.DEFAULT\Control Panel\Colors
4. Look at the value/data pairs, and if you see a large row of values that simply have "0 0 0" as their value - your problem is simple to fix.
   (example:
        ActiveBorder     REG_SZ    0 0 0
        ActiveTitle      REG_SZ    0 0 0
        AppWorkSpace     REG_SZ    0 0 0
        .....)
5. Under the My Computer node (your local server) navigate to the same location.  You'll see that the values have color data specified.  Right-click the Colors key and select Export.  Save the file locally as either a "Registration Files (*.reg)" or a "Win9x/NT 4 Registration Files (*.reg)" which is pretty  much just a difference between Unicode and ASCII, the latter format being easier to edit.
6. Once saved, select "Import..." from the File menu (it does not matter what key or computer you have in the active focus).
7. Browse to your saved file and open it.  You will be presented with a dialog similar to the following:
   
8. Select the attached computer, and allow the import to happen.  
9. The values are there, and will take affect immediately if you use Terminal Services / Remote Desktop to connect, but will require a reboot of the server to change local session.

A quick solution to an issue that causes way more stress to the administrator then deserved.  The download contains an export of a healthy server's out-of-the-box default color scheme in the event you do not have a spare or untainted Windows 2003 server.