XXP4 blend: error and crash on exiting attributes dialog

[The Alien]

I'm using XXP4, the original release (.4823), not the update. But I didn't read anything about this issue in the release notes of the update, so here goes:

1) Make a blend
2) Click either the Position profile button or the Attribute profile button
3) Press Esc and you may get an Access violation error (confirm?)
4) You may Quit to end it peacefully or click Continue.
(Press CTRL+Shift+T to redraw if you want)
5) If you try to continue by removing the blend and re-applying it, or by creating a new blend, you'll get the error:

An extremely serious error has occurred. Xara Xtreme must quit immediately. We apologise for any inconvenience caused.

And the program shuts down.

NOTE: at step #2, if I edit the attributes/position in the dialog (mess with the sliders), I notice that after releasing the mouse button, the attributes/position dialog loses focus. This is important, because if I press Esc now, the dialog safely disappears, though leaving behind some visual artifacts on the screen (the thick line of the blend). But in this case, no error appears and I can safely continue work.
If I go into this screen again and repeat the steps as described above (dialog has focus), the error occurs again.

Can anyone confirm any of this?

Specs:
1.3GHz Centrino
1Gb Ram
Intel integrated chip
XP Pro SP2