ff3usME error

Try re-downloading the mfc100u.dll and throw it in your dll folder.

This is not the correct way and you could install a non working or untrusted dll . You need to install Visual C++ redistribuables 2010 32-Bit or 64-Bit

x64 version: https://www.microsoft.com/en-ca/download...x?id=14632

This is likely not the problem if suddenly FF3usME stops working and you have not uninstalled the library from your OS.