CTRL + ALT + DEL
Task Manager button in the Windows Security dialog window that pops up.
Not Responding) you can manually kill it by selecting it in the Applications tab and clicking End Task. It may take up to 8 seconds for the program to close.
Processes tab. Look out for names that are just random strings of numbers and letters--those are usually spyware/viruses. You can also try looking them up on our XP Processes list, or look up the process on google.
Available value under Physical Memory (K) in the Performance tab. If this number is less than 50,000 you're probably experiencing a RAM shortage.
Cached and Free values under Physical Memory (MB) in the Performance tab. If these numbers combine to less than 50 you're probably experiencing a RAM shortage.