Use the following methods to resolve your pop ups error 81291 issues.
1.Right click on the Desktop, then select Personalize.
2.After you enter, you'll see Change desktop icons, Change mouse pointers and Change your account picture on the left column. They are normal desktop change items.You can enter into them and change according to your need.
1.After opening Firefox browser, click on Tool -> Option -> Content.
2.Locate Block pop-up windows, check or un-check to unable/disable popup block.
3.There is an Exceptions button on the right side, you can add some websites into it to receive their popup information.