fl studio and macbook 2008

i am using a macbook unibody 2008, with windows 7 64bit with bootcamp. i am having an annoying problem. when i have two instances of z3ta+ they almost cancel out everything else, like my drivers cant handle it. also when fl studio is open, and then i open anything that uses sound like my browser and youtube, it wont play any sound anywhere but fl studio. if i open youtube first, and then fl studio, it wont play anything in fl studio.
it does not happen on my friends older pc laptop. perhaps this is because windows 7 is not officially supported by apple for my specific computer, and i am using generic drivers. vista is supported though.. maybe i should switch to vista but its so bad.

if anyone has some suggestions, that would be great.