I will provide a fix for version 1.5.5 only. Unfortunately, I can't provide support for XP machines anymore. I switched to Win 7 on all my machines, but I'm happy that 1.5.7. still works on XP 
Nonetheless, I have to quote myself from the post above
Which means that the user has to download and install it directly from sourceforge.
I abandoned the updater due to security reasons.
Nonetheless, I have to quote myself from the post above
Nils Schmidt Wrote:If you are already using a version greater than 1.5.0 you can't update your installation by clicking on "Help -> Install Updates" anymore.
Which means that the user has to download and install it directly from sourceforge.
I abandoned the updater due to security reasons.