What are the causes of lockups with Debug on

What are the causes of system instability with Debug Turned on?
I'm developing on a Win2000 box.
I have 2 cameras.

When I try to run my code with Debug turned on I get what looks like a too fast refresh rate problem on my scren. Horozontol multicolored thin lines, Esc will not allow me out of the program. It runs fine with Debug turned off.

Blitz always runs apps in a window when debug is turned on. Maybe something to do with that. Perhaps your driver/Graphics card doesn't support 3D in windowed mode, or something. Check out these various commands:
CountGfxModes3D

GfxMode3D

GfxMode3DExists

GfxDriver3D

GfxDriverCaps3D

Windowed3D

Debug in Blitz3D tends to hang up the debugger for some reason here. Just locks up for unknown reasons and i have to kill the blitz compiler process to get it away again.

Tracer

There is the debug toolbar bit depth issue which seems to effect some windows versions. Changing the debug_toolbar.bmp to 24 bit solved my lockup problems.

Yeah, good call DJW! I'd forgotten about that one. :)

Thanks for all the responses. I really should have given more information. It appears to have started happening sometime after I added a second camera for a radar type view. I have not yet taken the time to deactivate the second camera to test if this is the issue.
When the code is run in BIDE 1.0.0.178 debug mode on, I get only a black screen. At least It doesn't make the whole system unresponsive as BlitzIde does.

Thanks for all the tips. When I figure it out i'll update here.