Issue After Downloading Security Update 2009-001

I just downloaded Security Update 2009-001 onto my iBook G4 and I'm having what seems to be a minor issue. Regardless of what app I'm running, I keep getting switched back to the Finder, like I used command+tab to switch between applications. It doesn't seem to be a major issue, but it's really annoying more than anything. Has anyone else run into this problem? Thanks in advance.

Update: I think Finder might be relaunching every few minutes or so. It looks like it's doing the same thing as when you relaunch it from the Force Quit window.

Anyone have any thoughts? Thanks.

some security updates have been causing glitches

Even if you already run 10.4.11, try downloading and running the combo update

Apple - Downloads - Mac OS X Updates - Mac OS X 10.4.11 Combo Update (PPC)

This often brings back stability to the os

Thanks for the help. I read that in an earlier thread and tried it but it didn't seem to fix the problem I was having. I found a few people on the Apple support website that were having the same problem. I turned off StuffIt AVR in the System Preferences and it seems to have fixed the issue. Here's a link to the thread on the Apple site if anyone else is having the same problem.