That’s why one should avoid sans serif typefaces that don’t have ‘bars’, e.g., the cross lines at the top and bottom of a capital I as in Illinois. Without that, the first three letters of Illinois look exactly the same.
That’s why Verdana is better than Arial, Helvetica, Univers, and Franklin Gothic… the usual choices for sans serif. Also, Verdana is much more readable when tiny than those other typefaces.
So, folks, right now, go to your web browser’s option window (under tools in FF) and change your default sans serif to Verdana (in FF, under the Content tab then Advanced button).