Sometime Plesk show following ERROR after login

Fatal error: Call to undefined function isKeyProp() in C:\Parallels\Plesk\admin\auto_prepend\auth.php3 on line 40

This problems normally comes due to conflicts/difference between Plesk DLL’s and System DLLS. This problem can be solved by replacing libeay32.dll and ssleay32.dll of the server with the DLL’s provided by Plesk.

Following are the steps to replace the file

1) Search for libeay32.dll and ssleay32.dll in %plesk_bin% folder (C:\Parallels\Plesk\admin\bin).

2) Stop Plesk Service.

3) copy and paste them to %windir%\system32 folder (C:\WINDOWS\System32).

4) Start Plesk Service.