Have you tried:
– deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the Twenty Eleven theme to rule out any theme-specific problems.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
Thank you very much!
Resetting the plugins folder seemed to fix it. It must have been ‘WP-Splash’ plugins that I had not been using at all since I only have 4 plugins. The remaining ones are working perfectly. I’m able to save, and delete without any errors.
Thanks again for your help.