1. Open an Internet browser window. This will allow you to uninstall the problem ActiveX control so you can reinstall later.
2.

Click on 'Tools' and choose 'Manage Add-Ons > Enable/Disable Add-Ons.' This will display all add-ons on your computer.
For Firefox, click 'Tools > Add-Ons.'

3. Select 'Downloaded ActiveX Controls' from the 'Show' drop-down list.
4. Select the ActiveX control you wish to delete. Once highlighted, click 'Delete' under the 'Delete ActiveX' box at the bottom-right corner of the screen.
For Firefox, click 'Uninstall' beside the control you want to remove.
5. Click 'OK' and visit the website you initially downloaded the ActiveX control from. If you don't remember the website, visit Microsoft.com and search for the name of the ActiveX control to find a safe download link. This will reinstall the ActiveX control correctly.