Comment 30 for bug 795626

Same happened to me. I was using boinc-client at the time (high CPU usage).
Kubuntu 12.04
kernel 3.2.0-23-generic x86_64
Laptop Acer TRAVELMATE 5744-383G32Mikk

Apr 13 00:50:59 Nevill-Acer kernel: [ 7155.341189] usb 1-1.4: USB disconnect, device number 4
Apr 13 00:51:03 Nevill-Acer kernel: [ 7160.398485] hub 1-1:1.0: hub_port_status failed (err = -110)
Apr 13 00:51:03 Nevill-Acer kernel: [ 7160.398491] hub_port_connect_change: 24 callbacks suppressed
Apr 13 00:51:03 Nevill-Acer kernel: [ 7160.398495] hub 1-1:1.0: connect-debounce failed, port 4 disabled
Apr 13 00:52:06 Nevill-Acer kernel: [ 7222.917475] usb 1-1.5: USB disconnect, device number 5
Apr 13 00:52:15 Nevill-Acer kernel: [ 7232.380481] usb 1-1.6: new low-speed USB device number 8 using ehci_hcd
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.528160] ehci_hcd 0000:00:1a.0: fatal error
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.532089] ehci_hcd 0000:00:1a.0: HC died; cleaning up
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.535051] ehci_hcd 0000:00:1a.0: force halt; handshake ffffc90000666024 00004000 00004000 -> -110
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.535057] ehci_hcd 0000:00:1a.0: HC died; cleaning up
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544070] usb 1-1.6: device descriptor read/all, error -108
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544126] hub 1-1:1.0: cannot disable port 6 (err = -19)
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544135] hub 1-1:1.0: cannot reset port 6 (err = -19)
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544141] hub 1-1:1.0: cannot disable port 6 (err = -19)
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544147] hub 1-1:1.0: unable to enumerate USB device on port 6
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544152] hub 1-1:1.0: cannot disable port 6 (err = -19)
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.544164] usb 1-1.3: USB disconnect, device number 3
Apr 13 00:52:16 Nevill-Acer kernel: [ 7232.652567] usb 1-1: USB disconnect, device number 2