My late 2011 15" MPB, running Mavericks 10.9.4, started running very slow. I ran verify disk in disk utility. I got the following error: Checking volume bitmap. Volume bitmap needs minor repair for orphaned blocks. Invalid volume free block count. (It should be 26319165 instead of 2217283) The volume Macintosh HD was found corrupt and needs to be repaired. A popup said: This disk needs to be repaired using the Recovery HD. Restart your computer, holding down the Command key and the R key until you see the Apple logo. When the OS X Utilities window appears, choose Disk Utility. Is there a chance that if I run the Disk Utility I'll completely screw up the disk? Any way to guess how bad this is? I've been doing backups with Carbon Copy Cloner. Should I re-install? Or will that just copy over the same problem?