charactered displayed as '?'

On some websites, when there's a ' (single quotation mark) or - (minus sign) they don't get displayed correctly.

For most of the times ' is displayed as a chinese character and - is displayed as ? (question mark).

Sometimes they even mess up the HTML, causing things like ?/font>

No other computers are like this. The only thing that's different on my computer is that I have Chinese installed on my home XP.

Anyone know what's the problem?

Thanks very much for helping me