Re-install a USB device

[Michael Hipp]

Does anyone know how to cause the OS to re-detect or re-install a USB device?

I have a USB modem that works great. But if the system is rebooted, the modem 
does not seem to be properly detected. The device /dev/ttyACM0 just isn't there 
as it should be. Anyone know how to get the system to look for the device and 
reinstall it? At present I have to physically remove and re-insert the USB plug 
to get it to work again after a reboot.

Thanks,
Michael