So far I only see a few things.

In your error log are over an over errors about a write lock on the search index. Are you sure the IIS web site is not configured as a web garden, ie only 1 processor should be allocated or it becomes a web garden. The index error cannot be related to the problem but if it is configured as a web garden it can cause other strange problems. You may want to try Rebuilding the Search Index.

The other thing I see is that for some pages you are using unsupported url structures with extra / segments like:

http://www.tswmainframe.de/db/cities/new-york.aspx

and

http://www.tswmainframe.de/chars/akma.aspx

These kinds of urls can cause problems and since some are in the same section (ie they have the same parent page) as the page with a problem, it is possibly related.

Other than that, right now I'm not seeing the problem it is working correctly at the moment as far as I can see. If you see any that are not working correctly it might be worth trying going into page settings and click save and see if that solves it.

Only other small thing I see is your admin toolbar has duplicated icons/links for some reason.

Best,

Joe