I tried to reformat by going to the command prompt and typing in "format c:" but it doesnt work. I get a message saying " Format cannot run because the vlume is in use by another process. Format may run if this volume is dismounted first. ALL OPENED HANDLES TO THIS VOLUME WOULD THEN BE INVALID.Would you like to force a dismount on this volume? <Y/N>" After typing in Y it says "cannot lock the drive, the volume is still in use." What should i do??