[Nottingham] dual boot conflicts

[James Gibbon]

Does anyone else experience difficulties when booting from one OS to
another in a dual-boot setup?

I installed Fedora Core 2 on my Sony laptop yesterday, overwriting
Slack 9.1.  Unfortunately, rebooting from Slack to XP causes XP to hang
on startup - black screen, flashing cursor.  Powering down and restarting
brings up a 'start windows normally' option, after selectign which, XP
starts up perfectly.

I'm not 100% certain but I think booting the other way causes problems
for Fedora too - on at least one occasion anyway, Fedora came up with
sound not working - though I can't be sure that warm-booting from XP
was responsible.

Either OS will start up fine after powering down all the way then powering
back up.  I don't think I ever had to do this when Slackware was installed.

Any ideas what causes this, or how to avoid it?  Are XP and Fedora fighting
over some chunk of non-volatile memory somewhere that they need to control
to start properly?

Ta
James