I did a quick look online and see that other people have had your problem. Have you tried Acer support yet? I once worked on a friend's Acer laptop and found that their support was decent: http://www.acersupport.com/us/en/produc ... aspx?tab=1
It could be that the drive is starting to go or is dirty. Have you tried cleaning it with a lens cleaning CD?
If it seems more software-related you can try System Restore to a point prior to your trouble. Also, you can try the system file checker utility. This is how to run SFC, as posted by Gary elsewhere on this board:
"Try running the System File Checker which will replace and missing or
corrupt system files.
Go to Start and type cmd.exe In the results, right click the cmd.exe
file and select the Run As Administrator option. In the command dialog, type
Did you recently install any software or do any other changes to your system that might be causing conflicts?