Viruses or false positives with Superantispyware?

My Widows XP Pro stopped working. It gets to the Windows splash screen
and reboots. Running Superantispyware from the Windows 7 part of the
dual boot it showed three different Trojan viruses on the Windows XP drive.
Trojan.Agent/Gen-Bumat
Trojan.Agent/Gen-Orsam
Trojan.Agent/Gen-Sirefef
It says it cleaned them but they show in the next scan after rebooting.
This happened three times, it would show them removed and they were
back.
I updated to a newer version of Superantispyware and those Trojans
were no longer found but six others were listed. After a reboot, it seems
as those are gone now. Another scan is running.
I've never had a Trojan on any of my computers and wonder if they are
false positives. I've never had a problem with the program, either, and
hope this isn't a new ongoing problem...