Can't tell about Opera(Blink) 18 which I don't use but AFAIK "EasyHK32.dll" isn't part of Windows OS.

That's for sure..

I downloaded the library file and put it into the system32 directory. After registering the dll, it still persists. Except that, everything runs perfect.

If you're doing that often.. Hopefully you're keeping track of what DLLs have been regged (many times it will be incompatible with the program(s) / OS; which could've, actually, been your problem there); but, more importantly, analysing the file itself - prior to executing any commands. Way too often has there been a virus, packed as a useful DLL (or as a needed one :))

I believe the dll file name stands for "easy hook".