You could make your own message box as a form. Then you could customize about anything with it or use a timer event on that to close it and continue your code.

If your user Alt-Tabs away from Access (which they are likely to do when idle), then SendKeys will send keystrokes to the application being Alt-Tabbed to instead.  So I'm not a fan of this method.  A better method is Adam's suggestion: create your own form for the message box that you can close with VBA (DoCmd.Close ...) instead of having to close with a keystroke.

While the two suggestions were coming in, I did a test with the message box and a timer. The timer never got to run, so the modal message box stops all VBA code until OK is pressed. So, the timer trying to use sendkeys would never run. So yes, I've got a status box on the form, and with some work, in there goes the message. Thanks guys.