Mouse pauses before responding

I have a user who went out and got herself a new keyboard and plugged

it in. After she plugged it in, she says her mouse pauses for a couple

of seconds before responding if she doesn't use it for a few seconds.

I ran the install program for the keyboard, shut down, restarted,

tried her old keyboard--the problem persists through all of those

changes. Ideas? It's almost like the mouse goes to sleep and takes a

bit to wake up. It is a USB mouse and keyboard.

Thank.