Problem with PC Boot

[wrhenders]

When I boot up my desktop computer, it runs through the BIOS and then goes to a black screen with a blinking _ and wont let me input anything. This happened after years of working fine and no new installations, but the computer screen abruptly turned black while working on it and after a restart I got this boot problem. In the BIOS the MoBo recognizes the all the hardware, and when I try to boot from the windows cd it asks to hit a key to boot from the cd and when I do it just goes to the black screen with the blinking cursor...
Is this a hardware problem with the MoBo? or a software problem??
Thanks for any help!

 

[Tedster]

when's the last time you replaced the CMOS battery?

 

[wrhenders]

I havn't yet, its been three years, but the bios still has the system time and all that running fine. Would the battery effect the boot sequence directly?