Well, I"m hoping this is something very simple but i can't figure it out.  I copied (save as) my project to a thumb drive and then opened it in my other computer to play (I've done this before without problems) and it won't play or record,  The audio engine is working but no audio signal coming in.  And. if I try to records something it won't record.  I wonder if I have a corrupt file..  I checked all the audio paths under preferences and folder options and everything looks good.  What am I missing here.  I can see the audio and midi waves and such but no signal.  What to do??  Or if anyone can lead me to another thread.
Thanks for you response..

Do both systems have identical interfaces and I/O assignments? If you see signal on the Master bus, and don't hear anything, my first guess would be that the output of the Master bus is to an interface or channels that you're not monitoring.

Exactly. It's no problem moving a project to another computer if you have both the CWP and the audio folder in there. 
But that project will default to what every interface set up you used on the original. 
All is good if they are similar in/ outs but often all your in/outs can be changed. 
Example I can switch between my Tascam and Scarlett no problem, But old projects I composed using an M Audio interface will be silent until I re assign the outputs. It defaults to SPDIF because that was what I used back then. 
 
Look at your Master buss first. 
Also check in preferences and your Audio set up. 

Reboot - is the audio engine icon running?  

Audio engine working.  Absolutely no signal coming in and my inputs are set to my Presonus Audiobox in and out.
What I ended up doing was export all the audio files to my computer then importing them into a new project and that worked for me but I know there is a simpler way..