"Is there another way to alert Apple to this problem besides calling AppleCare?"
leogirl,
Apple is aware, as following the 10.4.8 Update, Apple listed on the Intel-based iMac Support main page (under "Popular Articles") an article containing their suggestion for a fix.
http://docs.info.apple.com/article.html?artnum=304482 Many users have found that it does provide at least some relief.
Combined with another fix posted in a few other threads concerning this issue, plus also adding on a re-run of the 10.4.8 Combo Update, I have had a big improvement, although not yet had a return to complete functionality. It's gotten good enough that it's not causing me any problem, since I turn off AirPort prior to initiating restart or shutdown. [Afterwards, turning it back on always works.]