I bought the game today on sale - and loaded it up only to find that it crashes every time I try running it.

Any help would be appreciated - otherwise I'll just end up returning it.

Did you installed a modern engine? No? do so.

Download and install quakespasm.

You only need this files:
id1/pak0.pak
id1/pak1.pak
hipnotic/pak0.pak
rogue/pak0.pak

Copy them in the quakespasm directory.

If you want the music, check the other thread.