Device Manager Blank – Mouse and keyboard unresponsive

A customer brought in an XP machine that was infected with a virus (they didn’t not which one.) We had supported them over the phone briefly, and due to an issue where the device manager was blank, we wanted them to bring it in. Turns out that now we aren’t able to get the mouse and keyboard to work. After doing some research, I found that this a symptom of plug-n-play service being disabled due to virus or spyware activity. Restarting the PnP service can go a long way to fixing this problem. BUT…can’t do it without a keyboard and mouse.
I am able to get into the BIOS and get it into safe mode,so the hardware works. BUT after Windows starts, its no go. Any suggestions?
Thanks!