A Bunch of Command Prompts Open On Start Up, Then Freezes

I've been trying to clean out my aunt's old emachine since it's been really slow. I did the usual disk cleanup, defragmenting, turned off unnecessary start up programs and so on. I also ran spybot and it found some stuff and removed them. Now when I boot up, Windows loads, but only a few seconds after the desktop loads a whole bunch of command prompts (CMD.exe, command.com) open rapidly and then the computer freezes. The last command prompt that opens before it freezes says something like "the system cannot find the file specified". I don't even have time to do anything before this all happens and am forced to reboot. Does anyone know what this might be? I can go into safe mode just fine but what should I try from there?

The basic pc specs are: emachines model T3116, Windows XP Home SP2, 2 GHz AMD Sempron 3300+, 1.5 gb ram, an old GeForce MX440 64mb video card.

Thanks for any help you can offer.