FSX Steam Edition (not responding)

Hi,
Can anyone give me any advice on the above situation please ?
Until last week all was running fine
.I get the opening FSX Steam Edition screen then answer a couple of the usual warnings with yes then it just hangs for hours saying in upper left hand corner (not responding)
I'm running win 7 64 bit with Matrox triple screen DE .
I have re-downloaded from Steam 3 times but still locking out !
All the best