I always run w/ minimize to tray/Esc to minimize and have not seen this problem (Windows XP SP2). I also was not able to reproduce on Windows 2000 SP4.
What exactly do you mean 'refusing to respond' and 'maximizing it'? What method(s) do you use to activate UR (hotkey, left-click on system tray icon, right-click system tray, Open UR)? It's doubtful the problem has anything to do with your database, but to verify that you could close it and open a sample DB and see if the problem still occurs.
Can you post or send to
support@kinook.com the info from Help | About | Install Info and an export of the registry key HKEY_CURRENT_USER\Software\Kinook Software\Ultra Recall (using regedit)?
I'm not sure what the debug info from the second post is, but it's not coming from UR. Could you both try closing any active applications and other system tray applets to see if they might be interfering with UR? Thanks.