I have an HP Pavilion dv5000 with gOS/Ubuntu.
I have a USB keyboard and a wireless USB mouse (logitech) that work when individually plugged into USB ports. When I plug USB hub into one of the same USB ports and then plug the keyboard and mouse into the hub, they do not work,

I've tried changing parameters in the kernel boot command (removing quite and splash options, adding irqpoll, noapic) but these have no effect.

#dmesg|grep -i usb.
[ 13.117846] usbcore: registered new interface driver usbfs
[ 13.117871] usbcore: registered new interface driver hub
[ 13.131965] usbcore: registered new device driver usb
[ 13.166601] ohci_hcd: 2006 August 04 USB 1.1 'Open' Host Controller (OHCI) Driver
[ 13.166938] ohci_hcd 0000:00:13.0: new USB bus registered, assigned bus number 1
[ 13.225742] usb usb1: configuration #1 chosen from 1 choice
[ 13.225767] hub 1-0:1.0: USB hub found
[ 13.329645] ohci_hcd 0000:00:13.1: new USB bus registered, assigned bus number 2
[ 13.389511] usb usb2: configuration #1 chosen from 1 choice
[ 13.389540] hub 2-0:1.0: USB hub found
[ 13.493564] ehci_hcd 0000:00:13.2: new USB bus registered, assigned bus number 3
[ 13.633015] usb 1-1: new full speed USB device using ohci_hcd and address 2
[ 13.644990] ehci_hcd 0000:00:13.2: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
[ 13.645107] usb usb3: configuration #1 chosen from 1 choice
[ 13.645129] hub 3-0:1.0: USB hub found
[ 14.068379] usb 3-1: new high speed USB device using ehci_hcd and address 2
[ 29.198399] usb 3-1: device descriptor read/64, error -110
[ 94.648429] usb 3-1: device descriptor read/64, error -110
[ 94.864340] usb 3-1: new high speed USB device using ehci_hcd and address 3
[ 115.932192] usb 3-1: device descriptor read/64, error -110
[ 131.184327] usb 3-1: device descriptor read/64, error -110
[ 131.400327] usb 3-1: new high speed USB device using ehci_hcd and address 4
[ 141.832433] usb 3-1: device not accepting address 4, error -110
[ 141.944433] usb 3-1: new high speed USB device using ehci_hcd and address 5
[ 152.376525] usb 3-1: device not accepting address 5, error -110
[ 155.344557] hub 3-0:1.0: Cannot enable port 5. Maybe the USB cable is bad?
[ 158.312587] hub 3-0:1.0: Cannot enable port 5. Maybe the USB cable is bad?
[ 161.280618] hub 3-0:1.0: Cannot enable port 5. Maybe the USB cable is bad?
[ 164.248643] hub 3-0:1.0: Cannot enable port 5. Maybe the USB cable is bad?
[ 165.354110] hub 3-0:1.0: Cannot enable port 6. Maybe the USB cable is bad?
[ 166.226116] hub 3-0:1.0: Cannot enable port 6. Maybe the USB cable is bad?
[ 167.098127] hub 3-0:1.0: Cannot enable port 6. Maybe the USB cable is bad?
[ 167.970139] hub 3-0:1.0: Cannot enable port 6. Maybe the USB cable is bad?
[ 171.040727] hub 3-0:1.0: Cannot enable port 7. Maybe the USB cable is bad?
[ 174.008747] hub 3-0:1.0: Cannot enable port 7. Maybe the USB cable is bad?
[ 176.976765] hub 3-0:1.0: Cannot enable port 7. Maybe the USB cable is bad?
[ 179.944806] hub 3-0:1.0: Cannot enable port 7. Maybe the USB cable is bad?

How can I fix this?

Does keyboard or mouse work with the hub?
If so, there may not be enough power available. Try using a powered hub.

Tried just the mouse with the hub, but it still doesn't work.
This same hub works with mouse and kbd on a win xp machine.

linux is generally very sensible: If USB devices are asking for power, and it isn't reported as being supplied, then it may not be allowed to work, because it might be unreliable. That is the way it should be.

You tried the mouse, but what about the keyboard?

What we are trying to do here is isolate the "fault":
- Is it the hub?
- Is it the mouse?
- Is it the keyboard?
- Is it linux?

???

You are saying "they do not work" and
"How can I fix this?"

You are not helping us to help you: you need to use your intellect to isolate the "fault", provide us with useful information [Errr, did you try internet "search engine" perhaps?] and then ask us to help you correct it.

see: http://en.wikipedia.org/wiki/USB#Power

and:http://en.wikipedia.org/wiki/USB_hub#Power

I doubt it has anything to do with power. I have a similar situation. USB 2.0 hub, and attached to it a low speed KB, low speed mouse, full speed webcam and full speed mouse. This works fine in Windows.

In Linux, the two low speed devices work but the full speed devices do not work, unless I rmmod ehci_hcd. Then all four devices work.

Try unloading ehci_hcd. Your mouse/KB should work then, though you obviously lose high speed capability for other things. But it would help to figure out what is going on.