My teenagers vehemently denied eating any cookies... computer-based, at least. The empty cookie jar in the kitchen tells another tale...
Be that as it may, I'm glad to report that JohninKansas' suggestion seems to have helped. My 17 year old computer genius updated IE, waved his magic wand over the machine, fed it a few cookies, and I'm happy again. It seems to have solved a few other bugs as well (such as, why did Google sometimes decide to be unavailable?).
Thanks for all the suggestions!