blank frot site

Hi guys. I usually try to avoid, asking for help, but this time I can't find any reasonable solution.

The problem is: the front side of my gk_musicstate_quickstart_J!3 installation is completely blank, while the admin side works absolutely fine.

What I have done:
I have installed your gk_musicstate_quickstart_J!3 on my private server, where my other Joomla! installations generally work. This one does not. When I change
extension>template manager> to e.g. "Beez5 - Default"
the site becomes visible. I have tried two of your templates: gk_musicstate_quickstart_J!3 & gk_university_quickstart_J!3 The same effect with both. I would love to start using the university one...
Any solution ?
the website is http://leo.tychy.pl

After long digging deep I have found what makes the problem. It is if I turn on th option "Generate thumbnails" in advanced settings of Image-Show-GK4. The thing is, it is turned on by default, so it is hard to find, and by the way, I don't know what it should do, but it makes the front completely blank, which causes heart attack

Hi

This option resizes images to the dimentions given. Please check if You have a GD library installed on Your server. If it's causing problems keep it disabled. Probably Your server is not configured to use it.