Error: 'C:/build/swbuild/SJ/nightly/18.1std/625/l64/work/modelsim/eda/sim_lib/altera_mf.v' doesn't exist.

Our design uses Altera PLL_50_100 instance. I am using questasim for simulation. I have installed the Altera libraries. Compilation goes through, but simulation hangs with last line being: # Time: 9...