My sister and I both have Windows 7 but she has the Home and I have the Pro. We both downloaded the game " Columbus: Ghost of the Mystery Stone". The game will play on hers but not mine. Could the two versions make a difference?

I shouldn't make a difference, so no. When the game installed, did you place it in your User Folders? I don't have the game so I'm not sure where the default install location is, but if it installed to your Program Files folder it may cause issues.

It's also possible the download was corrupt, try downloading it again.

Is there a specific error message you see? Does it install but not launch?

No but 32-bit vs 64-bit might. Does your sister have the 32-bit version?

Make sure your antivirus isn't blocking it.

Also, if you got it from Big Fish, where to install games is one of the Options the Big Fish game Manager allows you.