Nobody's perfect, especially not me, but this bug in visual studio is not pretty. Apparently “Visual Studio .NET 2002 and Visual Studio .NET 2003 do not support a common output folder.” ?!
At least there are some workarounds, so I'll give 'em a shot...
When reading Andrew Whitten's Blog on C# build tools, I decided to try out BuildIt. For some time now certain MSI installer packages wern't installing correctly on my machine. I hit “next” and the installer simply responds with something like “The istaller couldn't continue because it was interrupted...”. Nothing I did got it working.
Today, on a gut feeling, I moved the MSI file to my drive's root. Suddenly it worked nicely. I assume this has something to do with Windows Server 2003 security, but using process explorer (from www.Sysinternals.com), I see that the installer does run under my user account which has full administrative privileges.
Well, at least I can install everything again.