I have an HP Pavilion dv4000 laptop that recently has been abruptly shutting off. Generally it will work just fine even if I have it on all day going between active and standby modes. However, I have found that doing certain tasks or running certain programs, particularly converting files (either within the hard drive or from a CD) with iTunes and running some internet based videos (but not all...Youtube has no problem, but it can't handle ComedyCentral.com) cause it to shut off often. I cannot recall a time when the computer has shut off doing a task other than one of these two things, though lately it has been having some other problems with programs freezing occasionally or error screens at shutdown, which may or may not be unrelated. Any thoughts?