I'm going through Low Quality Posts for the month at the following link:
I scroll to the bottom of the page, and click the "get 30 more" link. The "month" filter is lost.
If you look at the resulting URL, the
& which is why it can't parse further parameters.
&but the page is not set to XHTML.
&and browsing there works like a charm (keeps the filter), so that's clearly the issue.