I can't see some unicode characters for some reason.
I tried to fix this by getting Arial Unicode MS
font as suggested in here: Why does Firefox not render some characters?
Unfortunately it changed nothing.
I am having problems viewing this wikipedia page: http://en.wikipedia.org/wiki/Month
At this part the problem is visible:
Elsewhere I see arabic etc. letters perfectly! What can be the problem and how to fix it?
sans-serif
, which is set to Arial on my installation. I believe Windows (at least since 7; I'm unsure about earlier versions) may substitute some characters from other fonts. Also, apparently each Windows release adds new fonts and new scripts to existing fonts - so your running XP may be related. As for seeing those characters in other places, do you mean within Firefox or in other programs? Are they exactly the same characters?