My computer froze up last night so I turned it off. When I turned it back on all I get is a black screen with a flashing cursor in the left corner. Is the desktop toast?

Do the lights come on when you apply power and the disc spin or is it just a black screen with nothing going on?

Have you tried to start the computer with a bootable cd if you have one?

I'm not quite sure what operating system you are using but I'll assume you are using XP. It sounds like you have a corrupted driver. Reboot the machine. Right after you see the BIOS splash screen hit F8 on your keyboard. You should see two options that may help you:

Last known good hardware configuration.
Safe Mode

Try last know good hardware configuration first. This will roll back the drivers. Otherwise try safe mode and try the system restore function in XP. You will find this under:

Start
Programs
Accessories
System Tools

Try a restore from a week prior to your problem. Hopefully this will reset the driver for you. Good luck!