Either you have an old version of Esellerateengine.dll which was installed by another product that use Esellerate OR your antivirus has corrupted it trying to "heal" it, mistakenly identifying it as a threat.
First, check if you have any copies of the Esellerateengine.dll in the following folders:
C:\Windows
\YOURFSXFOLDER (usually C:\program files\Microsoft\etc....)
C:\ProgramData\Esellerate
Remove all copies, then reinstall either KLAX OR the Stand-Alone Addon Manager, that will reinstate only the correct version in the correct folder ( C:\ProgramData\Esellerate)