Could not load file or assembly" error & shows as "The system cannot find the path specified" and the application is logging Out

We are using a web application which suddenly pops up with "Could not load file or assembly" error & shows as "The system cannot find the path specified" and the application is logging Out . There were no changes in the Application and Database. Below are the patches which were latesly updated on the server and post updation of the same these errors were Popping Up. Let us know whether these patch update are source for the errors that are observed.
Server Details: OS - Windows Server 2008 R2 Datacenter 64bit
IIS Version:7
.NET Based Application
Patches Updated for December 2013 Month: Description Fix Comments HotFixID Security Update. . KB2813430. Security Update. . KB2839894. Security Update. . KB2847311. Security Update. . KB2855844. Security Update. . KB2862152. Secur ...