Plesk login page keeps loading on Windows

Symptoms

1. Unable to login in Plesk. Login page is shown and after submitting credentials Plesk page keeps on loading. No errors recorded in logs.

2. Make sure that you have the following events in Windows Logs > Application:

   CONFIG_TEXT: Warning 8/12/2013 3:48:25 PM RestartManager 10010 None
   
   Application 'C:\\Program Files (x86)\\Parallels\\Plesk\\admin\\bin\\scheduled_backup.exe' (pid 6964) cannot be restarted - Application SID does not match Conductor SID..

   OR

   CONFIG_TEXT: Application 'C:\\Program Files (x86)\\Parallels\\Plesk\\admin\\bin\\php.exe' (pid 4316) cannot be restarted - Application SID does not match Conductor SID..

3. Windows Logs -> System

   CONFIG_TEXT: **Error 8/5/2013 12:29:06 PM HttpEvent 15002 None**
   Unable to write to the log file u_extend9.log for site W3SVC0. Disk may be full. If this is a network path, make sure that network connectivity is not broken.
   
   Warning 8/11/2013 8:01:50 PM srv 2013 None
   The C: disk is at or near capacity. You may need to delete some files.

Cause

1. Disk is at or near capacity.
2. Hanged php.exe processes.

Resolution

1. Connect to the server using RDP.

2. Check that it is enough free disk space on the server.

3. Kill hanged php.exe processes with CMD:

   C:\> taskkill /f /fi "imagename eq php.exe"
   SUCCESS: The process with PID 5276 has been terminated.
   SUCCESS: The process with PID 4220 has been terminated.
   SUCCESS: The process with PID 4316 has been terminated.
   SUCCESS: The process with PID 7128 has been terminated.
   SUCCESS: The process with PID 6772 has been terminated.
   SUCCESS: The process with PID 3668 has been terminated.
   SUCCESS: The process with PID 6384 has been terminated.
   SUCCESS: The process with PID 6296 has been terminated.
   SUCCESS: The process with PID 6152 has been terminated.
   SUCCESS: The process with PID 5584 has been terminated.
   SUCCESS: The process with PID 1884 has been terminated.
   SUCCESS: The process with PID 6792 has been terminated.