Windows

First: lots of questions.
Client-side JS or Server-side JS?
Your own code, or others?
All websites, or just some specifics?
Only the JavaScript dialogues or also your O/S's?

I would start by checking the language/locale versions of your O/S and your browser. You might be trying to display a "high byte" language in your dialogue, but you might be using a browser not capablel of that language version.

Dear eBob!
I M answering your reply in this manner as I do not have UR e-mail.
Regarding JavaScript, I M using Windows 98 on my home computer and only use it to surf the web (internet). The brouser I M using is NetScape Communicator 4.5, earlier all was fine then since last few months whenever, either I do a mistake ( e.g.: while composing e-mail left Subject line blank etc:) in using facilities or brouser want to caution me of my action, the JavaScript application Dialogiue Box appears, consists of rows of question marks.