404 error Page Not Found Message

I installed your image widget in the sidebar of my blog. I linked the image to another page so that people can go there to make a payment. The problem is that when you click on the sidebar image which is on my home page an error message comes up which says: 404 error Page Not Found Message .
What is more troubling is that sometimes clicking on the image does bring you to the right page – On my computer and sometimes I get the above error message.
However, it never seems to work on other computers the same error message always comes up.
Please help. I have deleted and re installed the widget several times and no change.

Thanks!