Neverending flashing underscore

Hey, my really old computer is having a problem. When I turn it on, it shows the little IBM logo and goes through the memory test and says

Press <ESC> to bypass system memory test and
Press <F1> to go to System Setup

I've tried pressing both buttons but it doesn't do anything. From there it goes to a little flashing underscore ( _ ) and never does anything. I can hit control+alt+delete and restart it but that is about it.

I tried putting a boot disk in but that didn't work.

Specs:

IBM Aptiva
Pentium 233mhz
Windows 95
64mb RAM