Sometimes other plugins or themes can cause problems with the Quform plugin. You can find the origin of the conflict using the following simple method:
1. Go to Plugins → Installed Plugins on the WordPress menu and temporarily deactivate all other plugins (except Quform).
2. Go to Appearance → Themes on the WordPress menu and activate one of the default WordPress themes.
3. Check if the problem is fixed. If the problem is fixed go to Step 4.
4. Activate the original theme again and check the problem again. If the problem is occurring again then there is a conflict with the theme. If the problem is fixed, go to Step 5.
5. Activate one of the previously active plugins and check the problem again. If the problem is occurring again then there is a conflict with last activated plugin.
6. Repeat Step 5 until the conflicting plugin is found.
If the problem still occurs with all other plugins deactivated and using one of the default WP themes, then the problem is not a conflict, please make a forum post explaining the problem and what you have tried.