I am running on Windows 8.1 64-bit OEM, and have installed Windows Updates and drivers for my system (the system was built just over a month ago).

This included drivers for a USB cellular modem (made by uBlox), and I mapped the virtual COM ports it enumerates to known locations using Device Manager (it happens to enumerate around 6 COM ports, I wanted these to number from COM11 through COM16).

I can see the location for this information in the registry at: HKLM\SYSTEM\CurrentControlSet\Enum\USB\VID_xxxx&PID_xxxx\...

Normally I run with the USB cellular modem powered off (and have left it in this state for a few days). Hence the USB cellular modem is only visible when showing "hidden devices" in Device Manager.

This week I left my system alone for a few hours and after rebooting and powering the USB cellular modem I noticed that the virtual COM port mapping I defined was lost.

I repeated this (by cloning a previous image of the harddrive and repeating) and it seems that Windows automatically removes the USB cellular modem from the system (i.e. it no longer appears as a device in Device Manager and all of the registry keys in HKLM\SYSTEM\CurrentControlSet\Enum\USB\... have been removed).

To be clear, this system has *only* Windows 8.1, Window Updates and drivers on it (no other 3rd party software, and no registry cleaners).

Does Windows 8.1 contain a mechanism to "clean-out" old USB devices (such as USB cellular modems) that it hasn't seen on the system for a period of time (as part of some house-keeping)?

Is there any mechanism in Windows 8.1 that can explain this behaviour?

Thanks