I get e-mails with a world which has a -field ending and it often becomes -feild or filed despite being up there clearly on the headed paper.

This is even more confusing now that I've moved to a new city where there is a Feild Hall at the university and a Feild Street (correct with this spelling), both presumably named after the same bishop. Children must grow up very confused here!

On the same thread...another problem which I recently discovered was "dose" and "does". I did my MSc thesis in medical physics where I kept talking about "radiation does" by mistake, and the spell-checker, of course, doesn't see this mistake. After several revisions I ceased to see it myself!

As I typed this I realized that I also tend to type "readiation". Argh.