possible hdd problem

My master is a 60gb maxtor and slave's a 160gb seagate. For some reason when I turn on teh computer it comes to the black(loading) screen and says "BOOT FAILURE, Insert system disk and press enter." Then I restarted the computer and it gets to the login screen, I login succcessfully and in about 10 mins the cpu freezes. Before it freezes theres weird noises comming from the computer (hdd I think). It sounds ike 'neet', like in MP and the holy grail, the knights who say 'neet'. Then, I turn the cpu off and unplug the seagate hdd, I turn it on and theres no problem. Right now, I switched the power wires on the 2 hdd's and its been running smoothly for about 10 mins now.

Was it a electronic "neet" or a grinding type squeel,had the same sort of noise coming from nephews comp today,so I reseated the graphics card, memory and unplugged and plugged back all cables,which seemed to cure it.

There was no problem with the pc yesterday, I left it on over night and when I turned onn the monitor, it was frozen. I restarted the pc and this message came up: A disk read error occured press CTRL+ALT+DEL to restart. I erstarted, then this message came up: NTLDR is missing Press CTRL+ALT+DEL to restart. I unplugged my 2nd hdd and turned on the pc again, this time it went straight to the bios and I forgot to write down the message but it was something about cpu frequencies. I discarded changes (2nd hdd not in) and it went to chkdsk, it went through deleting 2 files and it was working for 5 mins. then it froze, I restarted now with 2nd hdd plugged in and its working fine. I have no idea what to do please help.

try checking the hdd temps....using speedfan