i have sony vaio z. bought it 2yrs ago and this is my first major problem with this computer. it freezes A LOT. CPU is always running below 10% and about 2gb of my 4gb is used mostly. there is nothing wrong with the temperature either. sometimes it makes high pitched screeching noises from the base of the laptop. sounds like the hard drive but not sure. also when it freezes, the hard drive light stays on until it unfreezes. sometimes it freezes so hard that i have to force restart it. i have posted this concern on the malware section of this website and done a lot of virus scans and it came out clean. also, sometimes when it freezes, a black screen appears saying operating system not found, in which case i just force restart it again. when i click on vaio care application, an app i use once a week to clean my laptop, a pop up comes up saying external component has thrown an exception. and "to run VAIO care program, you need to log in to Windows with an account that has administrator privileges. VAIO care will exit." could it be that some of my applications are bugged?? thank you!!