Windows maintains a list of programs that automatically run every time you boot up your computer. Some of these startup programs (such as antivirus utilities) are beneficial, but many of them are not necessary and can slow your PC as they run automatically in the background. Speed up your boot time by .
This can happen for a lot of reasons--and unfortunately almost all of them are bad news. The most likely answer is that a fan or hard drive in your PC is starting to die, causing it to spin off-kilter. PCWorld contributing editor Lincoln Spector wrote a smart guide to pinpointing the source of a grinding-sound problem in this . No matter what the cause turns out to be, you should immediately , just in case.