Archive Links In Sitemap Generated are .html/ - gives 404 error

The archive links are ending in .html/ instead of just .html in the sitemap generated meaning Google finds errors with it.

How can I fix this problem?

EDIT:

Actually I can't be sure this is the problem as my sitemaps have a huge number of 404 not found errors.

Is there anyway I can get the sitemap generator to re-do everything, as some URL's may have changed?

The extra / in the archive is a vb bug:
[#VBIV-7517] Archive forums have an extra / on the end of the URL - vBulletin JIRA

Ah, well thanks for that. That's one error I can fix up at the moment.