Well reading through your virus description scares the hell out of me and here is why.
I thought most modern virus Writers couldn't figure out assembler, in the present days that was all they where written in. IF there are guys out there that can revive assembler viri they can modify the old stealth boot sector viri (form.a and what not). When those nasties get on your system AV's can't find them after your OS loads the only way to clean them is with a clean boot floppy with an AV(or knowledge of how big your boot sector is and a clean boot floppy with a mbr repair util). This is bad because I haven’t seen a AV that will fix on a boot floppy in seven years.