We can't know anything without proper system information and other details.
Sorry, my bad - totally forgot about that!
64-bit Windows 8.1
GeForce GTX 860M (4GB Dedicated RAM)
Need anything else?
Ah that makes sense now! Thanks.
Would it work if I ran it in compatibility mode?
Nope. Revert to an ealier operating system. CS 5.5 is three versions old now, and Adobe doesn't support old software forever.
I suspected so.
Thanks for your help guys!