Not made the upgrade to XP myself yet - I gather one thing you often have to do is disable XP's own burn engine.
At a minimum, by disabling XP's recording option for the drive (this only stops XP's NATIVE recording functions from using it, other software still can).
Or more extreme, by disabling XP's "IMAPI" recording service.
Some notes here
http://support.microsoft.com/default.aspx?scid=kb;en-us;q324129
Couldn't find a "worked example".
PS. Nero 6 is also rather buggy, but initial reports seem to be showing the latest release (6.0.0.23) to be better than most. If you have an older release, Updating may be useful - not so sure this isn't a problem that was fixed in a previous update.
And welcome to the forum.... I've moved the post to a more appropriate area.
It helps if you post in the area that best matches the topic, and if you specify versions of any software involved.... and please don't be a stranger after your problem is solved (please excuse grotty poetry!)