The question mark is a hint that you have a character encoding problem. My guess would be that your javascript files are saved in the wrong format. They must be UTF8. I would advise to simply overwrite the files in /js with the original files.
Most probably /js/library/jquery.popup.js, but if you see that question mark symbol in more places, you might have a server problem.
I do not know very much about how to solve the problem, but you will find more about it if you search the web for "character encoding"
in my forum 
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The question mark is a hint that you have a character encoding problem. My guess would be that your javascript files are saved in the wrong format. They must be UTF8. I would advise to simply overwrite the files in /js with the original files.
Which file occores the problem
Most probably /js/library/jquery.popup.js, but if you see that question mark symbol in more places, you might have a server problem.
I do not know very much about how to solve the problem, but you will find more about it if you search the web for "character encoding"