java.lang.UnsatisfiedLinkError: could not load i4jinst from C:\Program Files\NeoLoad 5.0\.install4j\i4jinst.dll, true, C:\Program Files\NeoLoad 5.0\platform.zip, false, C...
When do you have that error? If it's during the installation phase i would say that your installer file is corrupted.
You should try to download it again from the Neotys web...