data rate inconsistancies between PC/Mac

[BGrimm]

Hello all,
I just produced a couple QT files out of Premiere Pro 2 on a PC. Tested on three different PCs, I got data rates of around 1.1 Mb/s.

However, when I brought the DVDs to my client and loaded them onto her Mac, the data rates jumped to around 11 Mb/s. Completely unwatchable.

I'm using 3ivx compressor, I've tried dual and single pass, Premiere Pro 2, QT7.

I've made hundreds of quicktimes from 3DS Max (animations) and have never encountered this problem, however they have all been relatively small. Fairly new to video, I've never heard of data rate consistancies between Mac/PC.

Any help or resources very appreciated, this project is sinking the ship.

Thanks,
Brian