Embedded Virus?

I recently downloaded and started using portable firefox. I was very happy with it, so I loaded it onto a larger flash drive for actual travel use.

On the second drive, after reformatting and installing portableFF, when I launched the app my AntiVirus scanner shows the following alert:

Virus&Spy Protection has detected adaware.maxifiles..

From the Anti-virus website:

Maxifiles.com distributes spyware called Director. It runs hidden from the user and installs in a way to appear to be part of the operating system.

So I wiped the drive again, downloaded PFF from a different mirror, re-insatlled it, and get the same warning.

Has anybody else got this? Why does it happen? Can I fix it? Or is this just a glitch between the PFF and my AV/Firewall. I should re-state that this doesn't happen with the other flash drive, or other apps on the same flash drive.

Any thoughts?