Please help!! Boot Virus??

Hello everyone I'm new at these newsgroups but I really need an experienced
users help. I have a computer at my business that runs our whole voicemail
system so It is killing us to not have it working but heres the problem.
Every time I boot the computer it tells me that i have a boot virus and that
i need to put in a blank bootable floppy, so I made a boot floppy on a
windows xp computer, and then made my voicemail computer boot of the floppy,
and all that did was show the "A:\>" symbol and let me type dos commands and
I just dont know how to get rid of this boot virus please help me!! I REALLY
need my voicemail.

Thank you very much, Pace