WINDOWS 2000 SEMI LOCK UP

OPER. SYS. = WIN2K
IBM LAPTOP,A20P,130,544KB RAM, 700MGHZ PENT II,PHOENIX BIOS4,THINKPAD BIOS4
PROBLEM: OUTLOOK OPENED AND THEN CLOSED, SYSTEM GOES INTO A KIND OF SUSPEND MODE, MOUSE WORKS BUT APPLICATIONS WILL NOT OPEN, AS WELL AS MY COMPUTER ETC. START BUTTON WILL DISPLAY AND YOU CAN SHUTDOWN OR RESTART WHICH SEEMS TO BE THE ONLY WAY TO CONTINUE WORKING. TASK MANAGER SHOWS 99% SYSTEM IDLE,I HAVE DISABLED ANY FORM OF SLEEP OR SUSPEND TO NO AVAIL.