Heatsink problem

-I replaced the plastic piece (bracket) that hold the heat sink in place because the original piece cracked and fell off, on my Dell Dimension 2350.
-This is the piece i bought and replaced:

-I bought it from here:
http://cgi.ebay.com/Socket-478-HEATSINK-RETENTION-BRACKET-Module-Yellow-NEW_W0QQitemZ320195172517QQihZ011QQcategoryZ80149QQrdZ1QQssPageNameZWD1VQQcmdZViewItem?_trksid=p1638.m118#ebayphotohosting
-Now my PC turns off in about 8 seconds when it is turned on, after the replacement…
-I’m almost positive my heat sink itself is not damaged because for a few months after the piece broke I had tape holding down the heat sink and it worked fine.(Probably wasn’t the smartest thing to do.)
-Please, and Thanks to those who respond to try to help.
-Heres Pictures of my actual computer and the heat sink area.



Answer #1
Is the heatsink in firm contact with the processor and did you coat it with thermal paste ?