If you mean that you tried to copy or cut the font file & paste it into the Fonts folder, then yes - that's happened to me numerous times with other file types...even when the file in question isn't in use.

I have no clue what causes it & working around it makes me want to bang my head against the wall since I can't rename either usually.
Anyway whatever the cause, it shouldn't matter if you do things a bit differently.
1. Open your Fonts folder. (C:\Windows\Fonts
2. In the File menu of the Fonts folder, choose Install New Font.
3. In the lower left corner, change to the folder where your new font is stored.
4. Wait for the List of Fonts in the upper half of the box to populate.
5. Highlight the font you want to add & click OK.
I don't think you'll get the "in use" error when you do it this way.