For the first time ever something intruded my system for a short time.
It managed to enter TweakUi and disabled my cdrom-drive, in my case F:
So no application could find this drive anymore in its open-window.
No app, except : TC . . . .
"It" managed to enter TweakUI? Who is "it"?
There is a setting in TweakUI under "MY Computer-drives" where you can hide drive letters but this setting is Explorer related only.
You can still access those drives when manually entering the drive letter in Explorer, for example enter f: in address bar.
Actually you don't need TweakUI for that, you can change setting in registry, too under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer in entry "NoDrives". If you delete that one your drives are available again.