With Visual C++ Express 2008, the LIB environment variable is being ignored.

Question

We are using LDRA to unit test our source code. In our case LDRA is using cl.exe and link.exe from VC++ express 2008, on several machines setting the LIB environment variable allows link.exe to find the libraries we specify, some machines ignore the LIB environment variable. Does anyone know what would cause the LIB environment variable to be ignored by the VC++ linker?