I own 2 Seagate Barracude 7200 RPM 500 GB hard drives. Recently whenever I open certain partitions or save something from the Internet, there is a brief pause and I can hear a hard drive spin and then the computer responds normally. Also when it is very quiet I can frequently hear the platter 'grinding' for like 0.2 seconds. How to fix? Should I be worried? I would prefer repair to buying a new HDD.