keyboard unreponsive at login

[Nick]

When attempting to login to 14.04 the keyboard on my laptop is usually unresponsive. Caps lock seems to work and shows an exclamation mark in the login prompt but typing in the password box does nothing and pressing up/down keys to select a different user does not change the user.

It seems the only way to get around the problem is to click on the menu items in the top right corner (panel) and then the keyboard becomes responsive.

EDIT: Model info: HP Compaq 8510p

OTHER INFO:
1) Ubuntu Trusty Tahr (development branch) -- Release: 14.04
2) unity-greeter:
  Installed: 14.04.4-0ubuntu1
  Candidate: 14.04.4-0ubuntu1
  Version table:
 *** 14.04.4-0ubuntu1 0
        500 http://nz.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
        100 /var/lib/dpkg/status
3) I expected to be able to type in a password to login or select a different user (eg Guest).
4) Keyboard was unresponsive (except CAPS lock) until I clicked on panel menu items with mouse.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity-greeter 14.04.4-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-17.37-generic 3.13.6
Uname: Linux 3.13.0-17-generic x86_64
ApportVersion: 2.13.3-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Mar 17 12:35:45 2014
InstallationDate: Installed on 2014-03-13 (3 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140301)
SourcePackage: unity-greeter
UpgradeStatus: No upgrade log present (probably fresh install)

[Nick (soapduk)]

A recent software update seems to have fixed this issue. I have done two successful logins without having to click the mouse on the top panel indicators. Will report back if I have further difficulties.