Might be time to start comparing programs and drivers, etc. between your two computers to see if you have a common piece of software on both, then take it from there with troubleshooting. Perhaps audio drivers, video drivers, anti-virus, background utilities, etc.. Might be a conflict somewhere that corrupts your files since your partner now has the same issues on his machine.
Good luck.
PS - I don't like surprises like hangs and stutters on stage - that is why I choose to burn my songs to a cd and/or mp3 player and play them from there. Might still have a hiccup once in a while but a lot less likely.