OK, Just to let everybody know who might be interested:
Bandstand seems to be the problem.With Bandstand active I can build a songlist up to about 500 songs.After that XP crashes.
When I uncheck use DXI I can scan the folder and after that I can reactivate Bandstand.That works. Or I can use BIAB Finder.No Problem there.
What the reason for this is,I don't know.Maybe Bandstands overloads RAM with all the patches as the tunes scan??? Strange.