Running a good, constantly updated Anti-Virus program on your computers - server and workstations - is a must when looking into the potential risks in today's IT world. However, when installing Anti-Virus software on a computer, you also risk having issues with some of the services and applications that run on these computers, most specially with the server machines. Anti-Virus software scans and sometimes locks files on the computers, and when you scan these files, performance and operating system reliability problems may occur because of file locking.

--> Please see the rest on the blog :

http://www.petri.co.il/anti-virus-exclusionn-guidelines-for-microsoft-products.htm