Raid 5 array will not rebuild

Okay, if anyone can help, it would be GREATLY appreciated. I have a Dell PowerEdge 2650 server, (Domain Controller) with a Raid 5 made up of 3 Maxtor 73 Gig SCSI drives, with a Perc 3/Di controller. Started getting the event that Rebuild failed. Do not know why, never had a failed drive show up. No amber lights, nothing. It will try to rebuild for about 4 hours, then the server will just lock up, can't do anything, and have to power down without shutting down. Entered the Perc bios at startup and it showed drive 0:0 in light grey. WIll rebuild to about 4%, then start over. I have replaced this drive with a new drive of the same size, and THAT drive shows up as failed, with red lights and everything. Put the original drive back in, and same thing, rebuild fails, but I can still boot to the OS, which is Windows Server 2000. I am afraid that everything is going to crash to the point of not being able to boot, or I am going to lose another drive because of having to powerdown, and reboot, to access data. I do not have a backup of any of the system, only of the data and shared folders. I am new to Raid (forced in last year when we actualyl lost two drives). I guess what I am asking is, am I missing something when installing the new drive? Should I format it? I have learned by reading in this forum that I shouldn't initialize the drive, especially since it is a boot virtual disk. Any advise would help.

Thanks