This is a 2013 Sharepoint Server.
Steps Taken
1) File exists in the following location C:\Program Files\Common Files\microsoft shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\1033\STYLES\corev4.css
C:\Program Files\Common Files\microsoft shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\1033\STYLES\Themable\corev4.css
2) Language packs have been installed correctly
3) Incremental Crawl has been set to weekends only
4) IIS reset fixes the problem temporarily. After non business hours it appears again and continues until IIS reset.
Can any one help ?