Responsive dir theme – edit post > 404?

Hello

I just changed my theme to the responsive directory theme.

When I try to create a page or past and save it as draft or publish it, I get redirected to 404.

Also when I want to edit, 404 is the result and not possible to edit.

I have checked some posts here and noticed this probably is caused because of permalink issues.

i do not know what is meant with clear permalink cache, it is the first time that i hear about it. How do I do that?

I have tried almost anything, disabled all plugins, still same error.

I really do not know what to do to get this fixed. Can someone help me step by step how to fix this?

Thanks in advance

Ray
ps. do we need framework plugins? I really get nuts with all this tech talk, sorry 🙁