My IBM 600 memory troubles?

My IBM 600 (pentimum II MMX its either a 233 or 266 cpu) keeps shutting down with a variety of ever changing messages on a blue screen. I am able to briefly bring it back up in windows 2000 safemode. I ran a diagnositic first thinking it was the hard drive. then I ran the diagnostic for memory and got a red X with the following DEV 002 ERR 21 FRU 0020. So what does this mean besides being SOL?