They're probably not hanging but rather there was an error and C5 unfortunately just shows the "loading" spinner until they report completion (which never happens if there's an error). See this thread for more details and some possible solutions (just be careful with the solutions that require running database queries -- make sure you back up the database before trying them or you could be hosed!):
http://www.concrete5.org/community/forums/customizing_c5/index-sear...

Thank you very much...

It seems as though it marks the maintenance jobs as running, but fails to mark them as completed.

Even though i went through the source code to see if i could locate the problem, but for it was a bit out of my field.

So I might as well look into filling a bug report, or look into what has caused the problem.

Anyhow, the problem persist, so there is something wrong somewhere, even though i tried to follow some of suggestions from the thread you mentioned.

Regards

You could use the Network monitor on Chrome or Firefox (development tools or Firebug) to track whether the communication completes.

You can usually see what the error is by copying the URL at the bottom of that "jobs" list in the dashboard and pasting that into your browser address bar. It should display whatever errors occur. You may need to set your site to "Debug" mode in Dashboard -> Sitewide Settings -> Debug in order to see those though.

Sorry for being late, just had a lot of stuff to do at work.

I found a fatal error from PHP.

Something like this:
Fatal error: Cannot make static method AttributeKey::getList() non static in class CollectionAttributeKey in .../concrete/models/collection_attributes.php on line 193

Edit:

I just upgraded from 5.4.2.1 to 5.4.2.2 but it has yet to solve my problem.