When you get this error … something got really broken. I do not know the reason how I got this error – but actually an installation of some development tools are the reason for this ….
Microsoft looks for the location of its tools by looking at the env variable “VS100COMNTOOLS”. In my case this env variable is set, BUT starting a VS2010 command shell fails to set this variable – because the Microsoft script unset the variable first and then query the registry for the installation path and set it again.
To query the registry it uses the command “reg” and “reg” is located in c:\windows\system32. But this directory is NOT defined in the PATH variable content any more and therefore reg is not found.
The not finding of “reg” creates an error and VS100COMNTOOLS remains unset and the whole stuff is not working any more.
Therefore the missing of “c:\windows\system32″ in PATH is the reason for all these errors – but I still do not know, which tool installation broke that stuff.