Recently was tasked with updating passwords on an older SharePoint 2007 farm.  The fun part, Windows Server 2003 was the host OS.   I hit a wall right out of the gate when I tried to run my STSADM command.

STSADM.EXE -o updatefarmcredentials -identitytype configurableid -userlogin “domain\SP_Admin” -password Cool@Password

Error: Access Denied

What the $#%##, I know I have full access to the farm and databases.

In Windows Server 2003, to launch the command prompt, right-click and select Run As.  THEN, un-check Run this program with restricted access.  Now run the STSADM command again.