I need a plugin that shows SOME pages for members only

Hi there, It’s been a day and I am sorry if I have typos.

I have a client/friend who wants certain pages to be shown only to certain people. I have been using CAPA plug in so when they went to the page, they were instructed to put in their passwords/user and they would be able to continue. Its been working fine on all my pcs (windows 8, windows 7, with all the latest browsers at home however, sometimes on my friend’s pc which is windows 8 and has all the latest browsers etc..after putting in the password she gets a reload page or a page that says its basically saying epic fail.

I was wondering if there is a product plug in out there that someone can recommend, simple enough to work with it, doesn’t cost a million dollars that I can put on her site and so this can become a past issue.

thanks in advance.. k