explorer.exe does not start automatically in Windows

1. Logon as Administrator
2. Click on Start > type in Search box -> Regedit find at top - >Right Click on - RUN AS ADMINISTRATOR

Navigate to this key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

In RIGHT PANE double click SHELL - Value Data and the entry should only be explorer.exe .

• If you have ANY other info there please write it down and post it here, and of course change it to the above

Close Regedit and restart.

Also read :"The trust relationship between this workstation and the primary domain failed" error when you log in to Windows 7

Also read :D LINK BSNL ADSL modem infected by virus & Solution

• Finally,Open command prompt as administrator and Run 

sfc /scannow