I think the main problem is your combinaison of V5R6 and Windows XP.
With Windows XP, you should at least use V5R7.
Personally, I use only Windows Nt & 2000 with CATIA V5R6,R7 and R8 and I think Windows XP is not ready for CATIA.
If you still want to use that combinaison of product, you should...