There's a known bug in 5.4.1.1 that causes some trouble with the Sitemap. This was fixed with our 5.4.2 release, but if you're going to upgrade we (of course) recommend the latest, version 5.4.2.2.

I think this thread has some background info on the problem:
http://www.concrete5.org/community/forums/customizing_c5/sitemap-no...

Andrew chimes in towards the end with a link to the fix on github.

Hi Matt,

Note you indicated latest version is 5.4.2.2 but my dashboard tells me latest version to upgrade to is 5.4.2.1 ?

We haven't rolled out 5.4.2.2 for automatic dashboard updates yet, but 5.4.2.1 should work fine with php 5.3.x as well.

If you're interested in downloading 5.4.2.2, it's available here:

http://www.concrete5.org/developers/downloads/...

To get your site updated, you'd upload the zip to your /updates/ directory and expand it there. Then you'll be able to go to Dashboard > System and Maintenance > Update and you'll see an option to "install local update". As always, it's recommended that you back up your database before an upgrade.