I cannot change parent of article(it is always root)

Whenever I try to change parent of an article I receive this error: The process cannot access the file because it is being used by another process. (code: 32). It never happened before. Everything started working so weird. All my last articles have wrong parent even tough the theme is still working. This is happening in admin panel.

To be more precise I have the following structure: Blog(page) with parent root and under blog page I have articles(pages). Everything worked great, but today something strange happened. All files are there and are correct, but in admin panel whenever I go to any article, everything is messed up....I do not understand why this is happening.

Sorry for long text.....hope someone met this before.

This might be helpfull for some people: if you change this param_sep: ':' in user/config/system.yaml, admin panel will crash.....Is it possible to define 2 separators?

First, are you talking about in the admin or not?

Yes everything was acting weird in admin panel after I changed param_sep from ':' to anything else

Strange, I know some other guys are running Apache on windows and have successfully switched the param separator to ; with no issues.