Because that's a corrupt setup. Why should it be a factor, obviously it is
and something involved with that has triggered the message and is preventing
setup from continuing.
Installing an operating system doesn't fix issues you are having with a
setup and usually makes such problems worse so you should consider yourself
lucky you got the warning and attempt to fix the problem before moving on to
XP. Once the problem is resolved, before installing XP, while at your
current setup's desktop, be sure to place the XP CD in the drive, when the
setup screen appears, select "Check System Compatibility" as it may find
other software and/or hardware issues that might cause installation to halt
and, as a result cause you to lose everything on the drive to which are
trying to install XP.
