I was using Mathematica 3 in my Silicon Graphics workstation's X window for sometimes until the Mathematica is upgraded from version 3 to 4 recently. The Mathematica is running in a central server.
It shows i)''Startup Error: The Mathematica fonts are not properly installed in your system. Without these fonts, typeset mathematica expressions cannot be displayed properly.'' and also ii)''Startup Warning: Unable to find font with family Math1, weight Plain, slant Plain, and size 12. Substituting Courier.''
The NoteBook of Math displays ''@'' althought ''['' is typed.