For a couple of weeks or so, I have been making installers without using them to update my own trunk-install, mostly due to not having enough time to play myself.
Thus it has happened that I didn't realise I'd introduced an error into the Oolite.nsi script that controls the build, the last time I had to customise it after the developers made changes to Oolite.nsi.
If you run the installer and accept the offer to uninstall the old development build, instead of removing the old build, it will uninstall your 1.73.x installation, but will leave the registry keys for 1.73.x intact, whilst at the same time deleting the registry keys for the trunk build. This means that you will be unable to re-install 1.73.x as it will report an unsuccessful uninstall and quit.
It's not hard to spot, because your 1.73.x game will not work any longer. You will need to delete the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Oolite key from the registry before you can re-install 1.73.4
If you have not run into this yet, DO NOT USE THE INSTALLER TO UNINSTALL THE OLD DEV-BUILD!
This afternoon (it's 1.30am here) I will upload a new build which will work properly.
If you have already had your 1.73.x installation trashed by my installer and are unable to fix the problem yourself, PM me and I will help you to fix things.
I will probably post a step-by-step guide with pictures, detailing exactly how to correct the problem, in this thread
Apologies to all concerned for the inconvenience, and I'll get onto it the moment I get home from work this afternoon...
Edit to add:
This problem has been corrected with SVN 2613, uploaded today, 28 Sept 2009. It will now remove the old trunk build properly, whilst still leaving your GNUstep settings intact.
Faulty installers for versions r2479 - r2609 have been deleted from the website.
Due to the lack of response to date, I'm assuming that not too many people have been affected by this, so I will deal with any problems that arise on a case-by-case basis.. Please PM me if you are having difficulties.