80GB v 160GB

hello

I do video editing with Adobe Premier Pro 2.0 on Win XP and I find that if I try to write an AVI file during rendering to my 80GB external hard drive via USB1.1 it works fine but to try to write to the brand new same brand (Western Digital) 160GB external hard drive (partioned into two 80GB drives) it write fails.

Does this have something to do with the actual size of the 160GB hard disk or what?

Any experts have something that could help me?

Many thanks
Bruce