You were posting on this forum thread which associated with Better WP Security plugin.
Okay, lets back to your issue. There are things you may need to do:
- Reinstall your WordPress. To do it, goto menu > Dashboard > Updates > Re-install Now. Sometimes, some issues can be solved simply re-installing.
- Check if there is any plugin you use need to be updated. Make sure all are up to date.
- Try to Deactivate and then Activate one-by-one all the plugins you use. Some issues may be fixed by doing so too.
- If the things above can't solve you issue, you may need to disable all the plugins you use. Test if the problem still happens. If still happens, it might be something not compatible with your webhost, you probably need to contact them.
- If disabling all the plugins really solve your problem, then it means one (or some plugins) is the culprit. Then enable one-by-one to test which one is the source of problem.
- If you find the plugin causing the problem, then you can start a new thread post under related plugin forum.