We still didn't find the cause of the problem.
But the following helped some people:
Uninstall Divinity (make a backup of your savegames)
Install Divinity again
Apply
the latest patch (DO NOT APPLY THE PREVIOUS HOTFIXES)Load the savegame
We are looking further into the problem and we will release a fix the moment we find out how this can happen.
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Little remark:
"I made backups from my savegames and now I can’t load them anymore" --> When you copy the savegames from a CD to your HDD, the read-only flag is set by Windows, preventing Divine Divinity to open these files for writing. Clear the read-only flag by right clicking on the files, selecting properties, unchecking the read only flag and then clicking on apply.