Some malware may corrupt the .exe files association. The .exe files are executable files of most of applications.
In order to restore the .exe file association, Kaspersky Lab specialists have developed a special utility named CleanAutoRun.
File Association relates a file to an application capable of opening that file in the operating system.
File association with a particular application is performed based on the file extension. For example, a file with the .doc extension is associated with Microsoft Word, so if you double-click this file, then your system runs Microsoft Word and opens the file in this application.
A single file extension may have several associations for performing various actions. For example, a file with the .jpeg extension may be associated with several commands, so that Open opens a file in an image viewer, Edit opens up an image editing application, Print opens an application to print an image.
Some viruses can damage the file association of executable or command files or icon files. In such cases if you try to open such a file, a malicious program can be launched.