No way around it. This creates a headache for a whole lot of people and is a known shortcoming of the 7D. It's weird, really. Film cameras don't have the same problem: the Maxxum/Dynax 7 certainly doesn't.http://www.lulu.com/bearpaw
There's a free e-book on the 7D and flash photography available for download at that link. You'll have to register at the site. Small book, helpful in addressing certain issues with the flash. No workaround for the one addressed in this thread, however.
People have written to KM with the problem. Hopefully we'll be seeing another firmware update, unless the problem's hard-wired into the electronics, in which case... we won't.