Vostro 1310: Touchpad stops after resuming from standby

I have a strange problem with a Vostro 1310, the touchpad works fine unless the machine is resumed from standby at which point the touchpad refuses to work.  Sometimes tapping the keyboard will bring it back but nothing shows as wrong in device manager (eventlogs look fine as well), the keyboard works fine though and so will an extermal mouse.  I was suspicious of the battery as I've seen faulty batteries cause similar issues but it's no different when removed.  I've rebuilt the machine entirely on a spare hard drive but the fault is identical, I can't see it being a hardware fault with the touchpad itself as it always work when powering on from cold or hibernate but never works from standby.

Any thoughts as I'm stumped?

Thanks,

John