Hey,
I gotta ask...are you using a pirate or a legit version? Reason has copy protection built into it, if it gets bypassed all sorts of weird things can happen.
Years ago I was running a crack of Cubase 3.5, it performed very well on my machine for about a month until one day my MIDI devices were no longer functioning. Windows could see each port, and the transport bar lit up when I sent MIDI in and out of Cubase, but I couldn't trigger my synths or record anything.
I had to wipe my drive clean and reinstall Windows before I could get MIDI to work again...about a month later the same thing happened! I finally saved up enough money to buy a real version of Cubase (with a hardware dongle), and I've never had any problems like that since.
Take care,
Nick