New hardware found sound every restart-- no other info given.

Hi there, my last new-build bug to squash... Clean Windows 7 HP 64bit install (all updates downloaded), ASUS Sabertooth X79, all USB device drivers current

EVERY reboot, once Windows has loaded, I get the "found new hardware/USB plug in" sound-- but no wizard pops up to install software and there are no listed conflicts in my device manager. Everything seems to be running fine.

I've done several searches and it seems this is a common problem, but there doesn't seem to be many issues that don't involve the hardware wizard popup or any listed conflicts in hardware manager.

I have a Logitech G500 mouse and G510 keyboard-- I've read that sometimes Logitech's software does this, but I unplugged both USB devices to test and restarted. The chime still happened, suggesting it's not these USB devices.

Any ideas?