When Visual Studio 2005 upgrades an old project, it turns on a setting which tells the linker to create a manifest resource in your program file. This resource seems to express a dependency on a DLL version of the C/C++ standard libraries. This causes the system to refuse to load your program unless said DLL is present. Your users will get an error indicating something about an invalid configuration and suggesting they reinstall. Apparently, the relevant libraries are not present on Windows XP SP2 (I haven't checked Vista), which causes the system to believe it should not even try to run some otherwise perfectly good programs.
This is a particularly vexing because some applications, including some bundled with Windows, install these libraries, and it can be difficult to figure out why some systems fail and others do not. One such application is, you guessed it, VS2005, so you will never be able to reproduce this problem on the system with which you built your program. Another seems to be Internet Explorer 7, so anybody who's got automatic updates turned on won't be able to reproduce this problem, either. Anybody who's still running IE6 (or earlier) without VS2005 probably will not be able to run your program.
Adding insult to injury, my programs already contain carefully constructed manifest resources and/or have carefully chosen linker options so that they don't take external dependencies which may or may not be present on deployment systems.
Fortunately, the fix was simple. There's a new linker option which controls generating this manifest resource. I turned it off and things went back to normal. It seems I could also have directed users to the Microsoft web page where they may download the C/C++ runtime libraries from VS2005. (Perhaps Microsoft ought to add these libraries to Windows Update.) Or, it seems, I could have redistributed these libraries with my programs (after deciding I am compatible with the relevant legalese).
I understand why Microsoft would want to add the capability of generating a manifest resource to the linker, but I don't understand why they would want to turn it on by default in such an annoying way. This cost me hours. It's partly my fault for not reading the upgrade report carefully; it did mention something about manifests. Had I been super-careful, I would have looked deeper into this potential problem and perhaps found the actual problem earlier. But since it didn't cause any trouble right away, I was lulled into a false sense of security that Microsoft had not done anything risky to my project.
