svchost.exe is a Windows service providing operating system facilities to applications. An instance of svchost appears to be invoked by Firefox. (Evidence: disappears when Firefox is shut down.) The problem begins a short time after Firefox is started or is activated after a long sleep. Firefox gives up memory and svchost grabs memory, eventually eating all of it up (98-99% memory use). then svchost grabs cpu cycles, running at 50%. On my machine cpu cycles never exceed 51-52%. After running like this for five-ten minutes svchost backs down and eventually ceases. Sometimes the computer is just painfully slow during this event, but other times it is paralyzed, and only pushing the reset will recover. The problem arrived several months ago, perhaps with an "upgrade". Anyone else seen this?