WordPress doesn't save changes

Hey!

Hope I can find help here for my problem.

When i try to change numbers in a defined field in a post and hit save – the old value is entered again. This also happens if I delete the box and save.

I go into the MySQL database and find me the value and correct it, the value is also in the box. I go back to the post and press save – again the old value is entered (the value in the database is overwritten).

I have the PHPs and the database already checked – but everything is fine with these.

Have moved the WordPress installation to test on two different servers – and behold: on both servers everything works fine – the error described does not occur. (Always the same database used)

As soon as I put the site back on the “right” server the problem appears again.

I look forward to your suggestions – should anything be a little unclear, I can explain it different / more accurately.

Thank you!