My dell dimension recently started acting very weird.  It will not connect to the Internet, and everything is "jumpy".  When I move the mouse, it takes about half a second for it to catch up, comparible to a strobe light.  The sounds and music act the same way as well.  I called customer support but they thought it was an Internet problem, but we debugged it and the ethernet port checked out.  Does anyone have any ideas of what this problem might be?  Everything also takes much longer to start up and load.  Thanks in advance!