The Memory usage also shoots up to about 475k MB. This has happened over two computers, the first being a stock Dell Inspiron 1620 with Windows XP and this one being a stock HP G72 with Windows 7. I used a data transfer cable to transfer all settings from the first computer to this computer. The problem persisted through 2 updates (3.5>3.6>4.0). The only FF add-ons I have downloaded are NoScript and AdBlocker; I also have several unused toolbars downloaded from various other applications (Yahoo, Norton, and AVG) and frequently use the Google toolbar, which in an unrelated matter stopped saving my searches or suggesting searches while typing at the 4.0 upgrade. If you need any more information, I'd be happy to post it.