George Karnos
Ansys Employee

Gray screen usually means graphics driver needs updated/unsupported graphics card.

First, try the following:
Make sure no ANSYS Programs are running.
Under %APPDATA%\Ansys

a directory named v222 will exist.
Rename this directory to v222.old

Now try to run.
If this doesn't fix the issue, check on updating the graphics driver.
Also, were there any updates to the machines that dont work?