Thread Subject: Weird simulink bus-creator dialog box behavior

Hi,
I've been seeing a strange behavior in simulink where whenever I open a bus-creator dialog box (double-click), it takes a little while to come up and then when I change something and hit 'OK', it freezes up the whole simulink diagram for around 5 seconds!
I also noticed that if I hit 'Apply' instead of 'OK', the simulink diagram is available for editing immediately and the changes are taken into effect. However, the bus-creator window will remain in the background and if I close it, it will go back and freeze the simulink model again for 5 mins.
I'm using r2001a on win7 64 bit.

Any ideas?

Thanks!