Thankfully I backed up my EXE folder before using Huor's file.
Now restored from backup -> Launched FL -> Saw "Trying to read update information" -> After a second it changed to progress bar -> Progress bar went to 100% -> Launcher appeared again -> I could start multiplayer (but server still offline).
For the first time in the history of mankind the CF 2.0 Launcher Updater worked without problems on my Windows XP system!!!
(It worked correctly, right??)
Edit: Nope Launcher Updater is 2.0.0.4 and Freelancer is 2.1.0.4... Now after restart they are fighting each other again...
Edit2: I killed Freelancer.exe in task manager, then the updater worked -> now I have Freelancer is 2.1.0.5 and Launcher Updater 2.0.0.4.
Versions are swapped with those in Huor's notice above, but I can start the game without problems \o/
- Wanderer -