Ok, so I've been trying to figure out why my Mac mini has been extremely slow lately. I've found the reason, but the not the answer as to why and wondering if anyone else has seen this. I have 10.9.1 with all updates installed. I've done 3 clean installs with the same results after each install. I've found that when starting file copies to two different external drives (one USB and the other FireWire) the copy starts off fast (33.4 MB/sec) and then stops, completely. As in 0 bytes; absolutely nothing is being transferred. The copy window in Finder is still showing the file being copied and the associated progress bar. I've used Activity Monitor and iStat Menus to monitor and get the same results when copying to each drive and see the same results in each. When the copy unexpectedly halts, the system is very, very slow... everything beach balls, dock is unresponsive sometimes, menu items don't paint, etc. I see nothing interesting in the Console. Disk Utility says all disks are OK (including internal disk with OS and apps only on it). External disks are about 50% full on the USB and 66% full on the FireWire disk. Has anyone seen this issue before? Possible Mavericks bug? Possible drive failure? I'm at a loss as to what the source of the issue is. * Additional note: As I was writing this, I tried copying two large files from one external drive to the other... no issue, as speedy as can be. Could this be a read issue from my internal drive?