I suppose what you mean is that the main font is a symbol font, and not a serif/sans-serif font.

 

From all I can think of, this would be your answer.

 

You can set the main fonts via Dektop > Properties > Appearance tab > Advanced button > click the text title bars etc. and then change them to what you want. For title bars, it is Trebuchet MS and for the menu is Tahoma.

 

I don't know exactly, but try going to the restore point with all the symbol fonts, and try to manage your way to the msconfig.exe utility and then click the radio button for selective startup (last one) and disable all the checkmarks then restart it. That should start it up without any themes. You can then easily change the font from there.