Chris,
Oct 11 11:24:06 acer-aspire kernel: [ 7812.377726] uhci_hcd 0000:00:1d.1: >host controller process error, something bad happened! Oct 11 11:24:06 acer-aspire kernel: [ 7812.377751] uhci_hcd 0000:00:1d.1: >host controller halted, very bad! Oct 11 11:24:06 acer-aspire kernel: [ 7812.377781] uhci_hcd 0000:00:1d.1: >HC died; cleaning up
Is looks like the USB host controller is crashing. Maybe look for a firmware upgrade for it (or for the BIOS/mother board)?
Also when you say "identical" have you tried swapping around all combinations of wireless adapters and track balls on both machines to see if there is a pattern.
Tim.