XP in VirtualBox in Feisty

[Seakat]

I'm using VirtualBox in Ubuntu Feisty to run Win XP with Service Pack 2, 
and I'm reasonably satisfied with it.

In the standard way, I have configured VirtualBox to recognise real 
partitions using the NAT protocol (as well as a couple of USB drives). 
Windows then recognises these partitions accessed through NAT as local 
drives (even one in ext format!), and it will read from and write to 
them for a while. However, when I do intensive work with reading, 
writing, or copying, after a few seconds to a few minutes, Windows 
inevitably crashes, and I get a Microsoft blue window, which you can see 
at http://assoc.orange.fr/acro/VirtualBox/Win_XP.jpg.

It's in French, because my Win XP is a French version, while my 
VirtualBox and Linux Ubuntu are in en_US.

Has anyone else had this problem, or know how to get around it (apart 
from copying dossiers via a USB drive)? I've configured VirtualBox with 
the default base memory size 196 MB, video memory size 8 MB and Hard 
disks: Primary master XP.vdi (/home/ian/.VirtualBox/VDI of 9.77 GB)