Fonts and running applications
You should be aware that installing or uninstalling fonts while applications are open may lead to problems.
Some versions of applications, even the most famous, may ignore font changes happening in Windows while they are running, or lock the font list of the system, or even may crash when font changes are made.
Also, some application may use fonts in a private way, that is, not visible from other applications, thus preventing the manipulation of fonts that may seem unused.
It is wiser to close all open applications before making changes to the font list in Windows.
OT1 Font Manager caches the fonts it displays for efficiency, which may prevent you from doing operations on the font files outside of OT1 Font Manager while it is running. If this happens, note that you only need to minimize the program window to clear the cache without closing OT1 Font Manager.