Korey,
We haven't seen this issue in awhile. It happens if the Mathcad UniMath font is missing or corrupted. It used to happen if you uninstalled a later version of Mathcad, then it broke an earlier version. Did you uninstall Mathcad 15?
I suggest running Repair from the Control Panel > Programs and Features > Mathcad 15.
You could also try reinstalling just the Mathcad UniMath font.
If that doesn't work, try reinstalling the Symbol font. It may be missing or corrupted.
If you are still having problems, please write back and include your system information (OS and service pack) and what your video/graphics card drivers are.
Regards,
Mona