Try this, and let us know if it works. You don't say whether you're using Windows or Macintosh, so I'll assume Windows...
- Open Notepad.
- Copy this text and paste it into the empty Notepad document:
100=Arial
101=Symbol
102=MT Extra
103=Symbol
- Leave 101-103 as-is. Replace Arial with whatever font you want.
- Code2000 is a better font for 102 ("extra math") than MT Extra is. If you have Code2000, I recommend using it. If you don't have it, you can get it here: http://www.fontspace.com/james-kass/code2000. It's free for personal use.
- SAVE THE FILE with this name: FontMapping.opt, making sure to switch the Save as type: to All Files. If you do not do this, the file will end up being named FontMapping.opt.txt, and it will not work. The directory to save it to is your "user home" directory:
- For Windows 7/Vista: C:\Users\{username}
- For Windows XP: C:\Documents and Settings\{username}
That should do it!