It is possible some 3dsmax is still stuck and running, or that you have 3dsmax started by for example vray spawner.
You can press WinKey+R, type in taskkill /T /F /IM 3dsmax.exe
and press enter. This will kill all 3dsmax processes running at your computer. But note that this might kill any rendering jobs that might be running on the PC, as well as close all opened scenes without saving, so use it at your own risk