Surround sound hassle

[Tomayo1]

Hi Chaps,
OK here's a stupid beginers type question. Having just downloaded some nice shiny software (and offloaded the old cassette 4 track) I'm pretty impressed with my first attempt BUT...
I put it into the DVD player that I normally use as a stereo and it sounded awfull. The problem was that it was in Dolby 5.1 mode and I mixed it for stereo. I can switch the sound system to stereo and it's fine but all my normal (i.e. professional) CDs seem to sound ok without having to do so. Am I missing a trick here?
Cheers
T