cubase hangs when zooming in key editor

Ive tried a search but with not much luck. The search feature doesn’t seem to be working at all on this end… oh well.
I ve been trying to create some drones for double bass practice using one of the pads in halion se - organic pad i think. Ive wanted each drone to be 5 minutes long, then export. When I’m in key editor and attempt to minimise the view to fit in 5 minutes on the screen to draw a 5 minute note, cubase hangs until I have to force quit. Really frustrating… any ideas.