Build doesn't work, but Rebuild does

[Raildex]

In Visual Studio, I can’t build my Solution.
I get this error:

C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(41,5): error MSB3075: The command “”//PathToProjectFile//" -waitmutex" exited with code 5. Please verify that you have sufficient rights to run this command.

Rebuild Solution on the other hand works.
But Rebuild takes way too long (~300 seconds).

Any solution?