Blank page after rebuilding the sitemap manually

I run WP 2.1 and Google Sitemap Generator 3.0b6.
When clicking the “rebuild the sitemap manually” link (in the admin area) I get a blank page as a result but the sitemap files appear to be properly generated.

Is this the normal behavior? (looking at the source of the page it looks like this is not normal since the body and html tags are not closed.)

I tested this on both Firefox 2 and IE6: same result.
Finally I should mention that I have less than 50 posts in WordPress so I assume this is not a memory issue.

Thanks for any help.

/phil