Illustrator CS3 check for missing fonts

I would like to be able to open Illustrator files and then check if there’re any fonts missing in the document. I have turned the user interaction off so that no dialogs appear when opening a document with fonts missing. I thought I might be able to check for missing fonts using the “Text font properties”, but it doesn’t matter what syntax I use Illustrator always errors. I think this is because Illustrator can only get the Text font properties of “An Installed Font”. As a last resort I tried extracting data from XMP string but it only seems to tell me the name of the fonts and not there status. Any advice on the syntax for “Text font properties” or a workaround would be much appreciated.

on AnalyzeDocumentFonts() – Generates a list of document fonts and missing fonts
tell application “Adobe Illustrator”
set documentProperties to (get XMP string of current document)

	set documentFonts to {} -- Global variable
	set missingFonts to {} -- Global variable
	repeat with x from 1 to count of paragraph in documentProperties
		if paragraph x of documentProperties contains "fontName" then
			set continueCount to x
			set fontNameChars to every character in paragraph x in documentProperties
			set fontName to text 35 thru -18 of fontNameChars as string -- Extracts characters from <stFnt:fontName>GillSans-ExtraBold</stFnt:fontName>
			repeat with y from continueCount to (continueCount + 3)
				if paragraph y of documentProperties contains "fontType" then
					set fontTypeChars to every character in paragraph y in documentProperties -- Extracts characters from <stFnt:fontType>Unknown</stFnt:fontType>
					set fontType to text 35 thru -18 of fontTypeChars as string
				end if
			end repeat
			if fontType = "Unknown" then
				set end of missingFonts to fontName -- Contains a list of all missing fonts in current document
				set end of documentFonts to fontName -- Contains a list of all fonts used in current document
			end if
		end if
	end repeat
end tell

end AnalyzeDocumentFonts