WP 2.1 MCE Editor – Mini letter type in editing window

I’ve just upgraded to WP 2.1. Since the upgrade, the window that one uses to type a post now uses a very small letter type. How can one solve this?

I’ve even tried a clean install in another directory, but the result is the same. Text is so small in the MCE editor that one can hardly see it!

I’ve tried a clean install on another server, and it works well.
Can a server not support the Javascript in WP 2.1?
I think I’m going to revert to WP 2.0.7.