I had been working on logo samples for my portfolio in Illustrator 10 on a PC and created a sketch file with four layers, and about ten font tests(each saying sandwich shop) on the first layer. When I closed the file last night a warning came up about not embedding two fonts, which are both freeware, so no surprise. Upon opening it this morning though, the file gave this warning: Can't open illustration. The illustration does not have the correct number of operands for an operator.I have opened the file using Notepad to remove the coding for the offending font, but it made things worse.
Perhaps the adobe forums may be a better source of help for you.
I saw the other post just now on the web that you had made about this a couple of weeks ago that had no help.