Problem with post edit screen (minor?): Visual editor

Hi everyone,

this is probably sth stupid on my side, but here’s the problem:

(WP 2.8) If I enter the edit post screen, the text is in the text box but I have to highlight it to make it visible. So, the text is not displayed (or displayed as “white”. This only happens in the visual editor mode and only on my PC (in all browsers I have, latest FF, IE and Opera).

Because there is someone else working on my site at the moment who has absolutely no problems, it must be sth on my PC (and not plugins, etc.)

The only programs I have running are the Commodo Firewall, Avira Antivirus … and that’s it.

Disabling FF add-ons etc. did not help at all.
Again, the same problem occurs on all browsers (IE, Opera, Firefox) in their latest versions.

I have no screen-capture etc. programs running.

I’m baffled.

I’m the only one who can’t edit anything because I can’t see the text. Anyone else who logs into the admin panel of my site from any other PC can see the text and edit it.

Does this problem sound familiar to anyone?

Any help or hint is appreciated.