Set DEVMGR_SHOW_NONPRESENT_DEVICES = 1

Due to the inexplicable registry of windows, many users find that after installing the Bluetooth management software, the corresponding Bluetooth virtual port is actually changed to COM9, or even COM13 or higher, as a result, the synchronization software with many applications, such as mobile phones and PDAs, cannot be used.
Multiple re-installation of the Bluetooth management software will only make the situation worse ..

The solution is as follows (before performing the following steps, be sure to uninstall the Bluetooth management program and reboot)
1. In Windows, press Start> RUN> Enter cmd and press Enter.
2. After the command character window appears, enter
Set DEVMGR_SHOW_NONPRESENT_DEVICES = 1
Press ENTER
Devmgmt. msc
Press ENTER
3. Click> View> display hidden devices in the Device Manager.
You can delete unnecessary ports now. After deleting the ports, Please restart them.

4. reinstall the Bluetooth management software.

5. If you want to permanently input this environment variable to XP, go to my computer> click, right-click, and choose Properties> advanced> environment variable
In the system variables, press "new", enter "DEVMGR_SHOW_NONPRESENT_DEVICES" in "variable name", and enter "1" in the variable value"