Yellow shrink button greys out in various apps

The little yellow "shrink to dock" button keeps de-activating, or "greying out" in various apps that are open after a few minutes of activity within the app. The only way to get it back is to close and re-open the app, but then it happens all over again. For example:

Camino:
Shrink button greys out after more than a few tabs are open, or sometimes just randomly during browsing.

Adium:
Contact list window and conversation window shrink buttons grey out after a few minutes of chatting with anyone.

Mail, Toast, Skype, and Terminal all do similar behaviors as well. The only app that does NOT seem to be affected is Finder itself.

I have a brand new MacBook Pro, 4GB of Ram, running OS X Leopard. Not sure if it matters but I also have a bootcamp partition and use VMWare Fusion to boot it up periodically within OS X when I need that occasional pesky windows app. The shrink button problem occurs whether or not VMWare Fusion is running though.

Anyone have any ideas as to what is going on?

I used to have this problem on Tiger on my iMac. Have you noticed if they all happen to occur at the same time? Quitting and reopening the program is a temporary fix. I still never found out what caused this. Leopard fixed this for me, thankfully.

You mean do all the shrink buttons grey out at the same time? No, they happen all completely at random within each app.