Template not working on some pages

Hello, I'm using the Coffee template on a site and this worked fine. But now the design isn't visible anymore on the homepage (http://eigenhandig.hisslink.nl). The other pages are OK, for example http://eigenhandig.hisslink.nl/index.php/contact.
What can be the problem?

The same thing is happening on another site, on which I'm using Postnote.

Please check server error log and Joomla log, this is probably related with your hosting.

Thanks, I'll look into that.
Also, the icon for frontend editing isn't showing on article pages. Any idea what causes this?

It seems these two problems are related. If I change the parameters of a component, the template doesn't show anymore. But when I don't change it, the editing icon is not visible on article pages.
The icon IS visible on blogpages.

I can not edit articles on most of the pages. The edit icon is not showing. This seems to be a template related problem, because there is no problem when I try it with the "Beez" template.
Also, the other problem doesn't occour then eighter.

Please help me out, the website is due this week. Thank you!

Anyone?

Please check server error log and Joomla log, this is probably related with your hosting.

Where can I find this info and what should I look for. I think it is pretty strange that some pages are okay and other aren't.
I couldn't find out the problem myself, so I purchased another subscribtion to post it on the forum, but now I don't get any respons anymore.