My configuration:
Windows Vista Ultimate 32-bit
WindowBlinds 5.50 build 102
ObjectDock 1.90 Plus
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Just wanted to add a quick note to this thread, just in case in might help someone. I was having this exact same problem. Whenever I closed an application, all of my docks (I have three, one of which is tabbed) would complete freeze up for at least 20 seconds and sometimes as long as a minute or 2.
Even though the docks were completely frozen and inaccessible, I could still use other programs. Since I have the windows taskbar hidden, I'd have to use SHIFT+TAB or WIN+TAB to switch between windows or to access minimize windows. Likewise, if I wanted to start an application that wasn't already running, I'd use the Windows key to access the Start menu. Very frustrating. I even tried a couple other dock applications, but couldn't find one with more than a fraction of the functionality of ObjectDock.
I tried everything I could think of, nothing seemed to work, and then, today, I simply ran the ObjectDock installer again. I didn't uninstall first; I just installed right over the top of my existing installation. And, (knock on wood) my problem seems to somehow have fixed itself. I've opened and closed programs like mad trying to recreate the problem, and I can't seem to do so. And it was omnipresent before, so this seems promising.