||This may be a little late to help with this situation but, I had the same problem and wanted to respond with the fix that I came up with.
I found that during the post installation process the giomgr.defs file was in some way being referenced by a component in the process. This seemed to be causing the problem. So, the work around that worked for me:
before running post installation setup
1) Navigate to your ArcSDE\sqlexe\etc folder
2) Make copies of the goimgr.defs, dbinit.sde, dbtune.sde files
3) rename files to
4) Run Post Installation Setup
5) at the ArcSDE Configuration files selection screen, select User Custom file and navigate to and select new copies of the configuration files.
6) Continue with the post installation setup.
Post Installation completes and the created ArcSDE service starts.