System: P2-400Mhz, Voodoo3 2000 PCI, Win98SE (unpatched)

When I run GLQuake with Glide, it runs perfectly, but at 640x400x16. Looks great, but there is an 80 pixel space at the top. I've tried creating an MS-DOS Prompt shortcut and adding -width 800 -height 600 to the end of the command line. What happens is it starts, I see the "Starting Quake" rectangle in the center of the screen, then I see the 3dfx logo, then I get a black screen with a mouse cursor. The mouse cursor moves around, but disappears towards the edges of the screen. I can't ALT-TAB back to the desktop, and CTRL-ALT-DEL does nothing. I have to hit the power button on the PC. I've also tried -width 1024 -height 768 and that does the same thing. These resolutions work fine on the Windows desktop, and they work in Half Life.

I've also tried opening an MS-DOS command prompt window, navigating to the Quake folder, and launching from there:
c:\windows\desktop\quake\glquake.exe -width 1024 -height 768
Same issue.

I'm running the AmigaMerlin drivers.

I've renamed the opengl32.dll driver in the folder to force the native Glide driver.

Any ideas?