I have a friend who was frustrated because in his extra resources, like grammars, that open in CHM files, all of the Greek and Hebrew characters were gibberish. After a long troubleshooting session I found the problem. I didn't find anything posted about it here, but I may have missed it.
NOTE: this doesn't fix the problem of Greek and Hebrew not showing correctly in your main BW window. This is only for the resources that pop up in a separate 'help' style window (CHM).
To fix your external resources font display (this is for Windows 7, Internet Explorer 9, Bibleworks 9 - it may work for others):
1) Open the resource that doesn't display correctly
2) Click the Options toolbar button at the top of the window
3) Choose "Internet options..."
4) click the "Accessibility" button
5) make sure that the top 3 options that refer to overriding fonts and styles are unchecked.
6) Click OK
7) Click OK
You should now see your resource formatted correctly.