After 10.6 install, double-press now needed for f9, f10?

Question

I have a MBP 2.4 GHx Intel Core 2 Duo, and finally upgraded to 10.6 (and 4GB of ram).  I used to be able to press F9 (and F10) to enable expose kfor all open windows (and all application-specific open windows).  Now when I press F9 (once) it looks like it it performs the function and immediately resets itself to the original window as if I had pressed the F9 button twice.  However, when I actually do press F9 twice, it does the quick function/reset then function again and stays on the screen.  F10 has the same problem.  Why do I need to press F9 twice in order for the function result to remain on the screen?
F11 and F12 work just fine ... no double-press needed.

Answer 1

Quoted from elsewhere on the web (link): See the note at the bottom as relates specifically to your query...
Short version:
In the Security pane of System Preferences, click the Advanced button in the Snow Leopard Firewall tab to get to the rest of the options found in the Leopard Firewall tab.
Longer version:
When Leopard arrived, Apple changed the interface to the Mac OS X firewall and caught a fair amount of flak as a result for the confusing way the options were offered. (It also made things worse by deciding to turn the firewall off by default.) In Snow Leopard, it has retained the application-based part of firewall services but has tried to simplify the presentation. The tab now opens with a note of whether the firewall is on or off, a Start/Stop button, and at the bottom, an Advanced button.
The Advanced button opens a sheet that present basically the same options as those found in Leopard. But Snow Leopard replaces Leopard's three confusing radio button options (Allow all incoming connections, Allow only essential services, and Set access for specific services and applications) with a single straightforward checkbox "Block all incoming connections." Below that is a scrolling list, carried over from Leopard, that shows which services have been made available (through the Sharing pane) and which specific applications have been either allowed or denied incoming access. As in Leopard, "essential services" (Bonjour, DHCP, and IPsec) are always allowed to accept incoming connections regardless of user settings, but you can now block access to File Sharing and other services.
Note: If you install Snow Leopard over an existing Leopard system, it will pick up your basic firewall settings (along with many other settings). However, if you do a clean install to a blank or erased disk, Snow Leopard will set the firewall to OFF by default, just as Leopard did.