Comment 4 for bug 624557

The part about files not uninstalling properly is due to a certain bug in the 0.47 uninstaller. It's been fixed in 0.48, so for the next release it will work properly; it shouldn't cause any significant problems.

The message box seems to be a by-product of the very poor uninstallation script used; it's been hacked about something awful to get checksums working with it, and not done quite consistently. I keep telling myself that sometime I'll rewrite it all decently, but I haven't got to it yet.

Explanation of the situation: AdvUninstLog.nsh thinks it's dealing with Uninstall.dat. However, this file is then read at the end and checksums calculated and Uninstall.log written. Then, once Uninstall.log is finished being written, Uninstall.dat is deleted as not needed. Unfortunately, whoever put it together didn't modify AdvUninstLog.nsh so that it looks for Uninstall.log rather than Uninstall.dat... so it's a bit broken. It won't generate a proper uninstallation log.

Also I observe from your second picture that $R1 is used in the LangString $(WANT_UNINSTALL_BEFORE) but it's not defined... that's why you get " wurde bereits installiert." Need to fix that.

In short, it's not badly broken (though the code is ghastly), but it needs fixing up some time.