So my macbook started running slow after I nearly filled the hd with tons of files from my external. I ended up erasing everything and reinstalling the OS through the internal recovery partition but my mac is still running slow. I ran an extended test with AHT and it found zero problems. I also used disk utility to repair the disk but it found no problems. It corrected a couple of things when i repaired the permissions but it didn't help speed up my computer at all. I also cleared log files and cache. I did a PRAM reset and I think I did an SMC reset but I wasn't sure if it worked because the MagSafe light didn't blink but the mac did restart when I pressed the keys. Does anyone have any idea what is wrong? I don't know what else to try and really need some help. I think I may have already made things worse. I copied the files from the mac back onto an external then zeroed out the mac hd. Afterwards I realized the files might be corrupted because the all of the songs can't play without pausing. I'm not sure if that can be fixed but I'm mainly worried about how my mac performs. Is there any way to fix it? Or do I have to get my hard drive replaced? Here's more info: -Macbook Pro Early 2011 -OS X Lion 10.7.5 -4GB DDR3 -2GHz Intel i7 Any help would be appreciated. Thank you.