New issue on the block after installing KB 973917. Checking event viewer you would end up with

Event Type: Warning
Event Source: W3SVC
Event Category: None
Event ID: 1009
Date:  12/9/2009
Time:  10:55:01 AM
User:  N/A
Computer: WEBSERVER01
Description:
A process serving application pool 'DefaultAppPool' terminated unexpectedly. The process id was '9878'.
The process exit code was '0xffffffff'. 

To resolve this problem, reinstall Service Pack 2 for Windows Server 2003 on the web server.

Check out KB http://support.microsoft.com/?kbid=2009746 

<UPDATE>

Before applying hotfix 973917 check whether it would break your IIS or not through this script

P.S: Script written by Punit Shah

</UPDATE>