Quicktime exports from Fcp

[Gorgorito]

I have recently experienced trouble with long files that FCP export in various files, the main file and a list of files finishing with -av1 and then -av2 and so on. Why is Final Cut Pro creating these extra files that complement the main one and why do I have so many problems when I want to transfer into wmv?

Why am I crashing with long files if I try to export as avi format, just happened as I was writing this SOS :-( I am using a PowerBook with Tiger, normally I use G5 could that be a reason?

Thanks for your help in advance.