I use slackware 14 64bit with stock kernel. Sometimes I got problems with using my external usb 3.0 2TB drive (ext4, LUKS-encrypted). After copying few GB from my drive it gets disconnected. When this happens I can't connect anything else to the same port until next reboot, I get only this in my logs:
hub 3-0:1.0: unable to enumerate USB device on port 2
However, sometimes I can copy 100GB file without problems. Another thing is that I have never encountered this problem when using Slackware 14 live boot DVD. Under windows 7 I had no problems too. So I can exclude usb port or hdd failure.
In encolsed log I got disconnected after copying 3GB of 100GB file.