All browser settings are at defaults (after all you did create a new, clean Profile)?
The only extension installed is NoScript?
All NoScript settings are at their defaults (after all you did create a new, clean Profile)?
What does about:plugins looks like?
A font issue that is affecting FF13 & not 12?
(The missing texts are in italics.)
Perhaps something like this (from our very own but absent of late al_9x), Bug 754452 - synthetic italics under GDI causes spacing problems for tahoma
There are a ton
of font related Preferences (& a ton of font related bugs
to go along with them
.) Perhaps a hammer approach might yield something? Disable gfx.direct2d.disabled (or enable it if it is disabled)? Pick some others & give them a whir.
Other then defaults, have you allowed any domains?
If you have not, thinking you should not even be seeing doubleclick.net yet.
And if you have allowed heise.de in some fashion, then you should not be seeing all 3 of the Allow options.
If you restart XP in Safe Mode (with networking) does the problem persist?
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:220.127.116.11) Gecko/20110420 SeaMonkey/2.0.14 Pinball NoScript FlashGot AdblockPlus
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120619 Firefox/15.0a2 SeaMonkey/2.12a2