They can't get to my blog – private blog.

Then I tried to get my blog to be private / locked, I have had a lot of problems. There is always someone who can not access it. Last time the problem has been the same for everyone who does not enter. They will only to a white page that says:

“You can not view this content in a frame.”

Very frustrating, I dont understand what is the problem. For some it works without problems, in any web browser. Some can only use Firefox, for some it does not work in Firefox with the explorer … with me, the blog works in all browsers.
Starting to get so damn sick … I want to read my blog, but like to be the ones who should have access to actually be able to read well. And my knowledge is not the best, so I really do not understand what could be the problem!

Could it be another plugin that sets it?
The problem may lie with those who can not access my blog, it’s a setting in their browser?