I am running snow leopard, have 8 GB RAM and 320GB hard drive I've had the computer 5 months, and today randomly decided to "repair disk permissions" on disk utility. Estimated time remaining is 32 mins. So far there is already a huge list of details, mostly things that are supposed to be set at 95 or 1 but are set to 0 (not sure what this means). Is it supposed to take this long? What exactly is it fixing, and how did these problems arise from simple regular use? Will I notice a difference in my computer's speed afterwords?