DB2JAVIT RC 9505, SQL5005C System Error, and failing vsai installation

If your favorite search engine brought you to this article, then you must be a .NET developer who installed IBM DB2 (Express) on a Windows Vista Box ... and then everything went wrong.

Here are a couple of symptoms that I experienced over the last couple of weeks, and how I solved them:

• If on every reboot after installation you get a SQL5005C System Error, then you should add your user account to the local DB2ADMNS or to the local DB2USERS group. These groups are created during the DB2 installation, but left empty.
• If some of the tools (like the Control Center) return a "DB2JAVIT : RC = 9505" error -or don't seem to do anything at all- then you should right click on the launch shortcut and select "Run as administrator".
• If you downloaded the IBM Database Addins for Visual Studio (from the file 'db2exc_vsai_952_WIN_x86.zip'), and the installer repeatedly fails with "a major error occured" without any further explanation or log file, then you should download the whole server: yes, the more than half a GigaByte IBM DB2 9.7 Data Server 90-days Trial ('v9.7_nt32_server.zip'). Unzip the Server/image/VSAI/Windows subfolder and install the Visual Studio Add-ins from there. This one successfully upgraded both my Visual Studio.NET installations (2005 & 2008).