Isn't that special.

Or should I say "that isn't special". The special characters in the dimensioning mode show incorrectly. The diameter symbol for instance looks like some weird text. Well this is a Window Font issue. Look for the AMGDT*.ttf fonts in the Windows\Font folder. If they are not there, copy them from a working computer or do a repair install of AutoCAD Mechanical and you should get them back. Congratulations, you are special again.