My unstable box becoming really unstable

My old Gateway 350Mhz Pentium II machine which has been running Debian unstable for ages is becoming really unstable. But it's not Debian which is causing the problems. Seems to be the Harddisk on which Debian is installed. Better get it up in the near future and see if there is any data that must be salvaged from this old machine. Main use of this machine was my old flatbed-scanner. Transfering the Firmware is also the most important thing to do. Otherwise I have to install Windoze somewhere to obtain the Firmware.