Cubase 6.5 refuses to launch (Win7 64)

I can launch Cubase 6.5 once and it works fine, but if I close it down and then come back later to work on a project some more, it refuses to launch a second time.

I checked the task manager and it says that Cubase is open, and taking up 10mb of RAM. If I close process via the task manager, it appears to work, but if I try to load Cubase again, it just does nothing and this process taking up roughly 10mb of RAM appears in the task manager again.

In order to launch Cubase a 2nd time, I am forced to reset the whole system. I know it isn’t a huge issue, but it is getting very frustrating.

Any help would be appreciated. Cheers!

Win7 64bit
Core i5 2500K @4.1Ghz
8GB DDR3 1600 RAM
Phonic Helix board 12 Firewire MKII