DC30+, Premiere5.1, problems

I'm using a DC30plus and have just felt confidant enough to upgrade from premiere 4.1 to 5.1 (I've had 5 since it came out but no drivers).

I've updated the latest drivers and everything appeared to be going fine

BUT....

I often capture at quite high rates then produce an AVI for use within powerpoint etc.
I'm experiancing problems with the quality of sound and picture using Cinepac compression. It seems to vary depending on the screen size I set.

Every now and then projects will only output audio through my soudcard rather than through the dc30plus.

Any ideas would be greatly appreciated.

Thanks

Ian.