Three weeks ago I bought 4 Vostro 1000's for the business.  I am having a problem with 2 of them (not sure about the other 2, since they went with since they with with someone else).  What mine is doing is when I boot all the way into Vista, it will dim down after 4 mins.  This happens either on battery or AC.  I do have the newest BIOS installed and installed newest video drivers with same results.  I also know about the Fn+ up arrow trick.  Please advise.