The patcher downloads the file to
I would put a copy of that file into %WINDIR%\system32. Since you already tried that you could also try dropping one copy into the Everquest 2\Mozilla folder but that should not be necessary. Actually I tried to reproduce the error with all copies of the file removed on my system and all worked fine (although it is true that the Mozilla libraries are linked to the file so there is potential for error). Make sure it's not your AntiVirus or some other software causing the problem.