Bizarre Final Cut Pro Problem

[animal]

Mystery deepens:  Two people have now told me my emails are infected 
with a virus.  I bought Norton Antivirus 9 for mac, installed it and 
downloaded the latest updates but cannot find any viruses or infected 
files.  Is it possible a virus is causing my FCP problem?  Is Norton 
good for all viruses?

These problems started last Monday after a fellow sent an .eml 
attachment which I tried to open but couldn't find the correct 
software.  When I contacted him he had no knowledge of the attachment.

Can a virus bugger my camcorder attached via firewire?  I need to find 
this out before I try daisy chaining and or get a new external hard 
drive.

Thanks
Lynn

PROBLEM:
Now - if I download 6 minutes or more to an external, every so often 
the 900MB or so clip is downloaded as a 65 - 98  GB clip and overloads 
my system.  Each time the external hard drive is left with 1.43GB.