@detz
Doesn't sound like a virus to me. The Amiga boots from its ROM, which I wouldn't have thought was accessible to a virus (? anyone). If nothing at all happens when you switch it on, check that the two ROM chips are properly seated.
Fitting a PowerFlyer requires the ROMs to be removed from the motherboard and remounted. This is a possible source of booting problems. Several people have commented that remounting the ROMs in the new sockets can be troublesome. Power Computing supply a couple of cable ties with the board to ensure the chips stay firmly in place. A bit of a botch IMO.
Why are you using pc formatted zips? I guess you run both pc and Amiga? If you aren't using a pc to transfer files to your Amiga, why not reformat the Zip with the native ffs or sfs, etc and see how they perform.
Just insert the Zip and format the disk in df6:
It will format just like a floppy.
Cheers,
JaX