connection interrupted when editing page

[swissdoode]

Hi Forum

I installed PW locally to get familiar with it, using one of the included demo-sites.
It all worked until I checked the checkbox to create new thumbnails for the homepage (in the admin-tool).
Now, whenever I try to edit the home-page, it seems like PW is doing tons of redirects and finally gives up and I'm presented with a «Connection interrupted»-error (in Firefox).
I tried different browsers, with the same result.

enabling the debug-mode in config didn't help either - no errors appear.

Guess something with that thumbnail-generator is wrong, but how do I fix this now? Is there some process stuck somewhere? I just wanna be able to edit that page again...

PW-Version 3.0.36
Apache on a Mac using ampps