Event ID 28721 in Source cannot be found

Problem:I have faced this problem when I tried to upload a document one of my document library in SharePoint. Neither the upload is successful nor no errors while uploading.
Event Log:I was unable to view any errors with respect to the document upload in the event log. I could see only the following logs in the event viewer:
Event Type: Error
Event Source: Windows SharePoint Services 3
Event Category: General
Event ID: 28721
User:  N/A
Description:The description for Event ID ( 28721 ) in Source ( Windows SharePoint Services 3 ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: #960013: Antivirus scanner timed out.

Following are the investigations done for fixing the errors:
1. Checked the file size limit in the web application general settings – but I have tried to upload only a few KB text file.
2. Checked the SQL server logs and there is enough space for the upload.
3. Created a new document library and tried attaching a new document which is unsuccessful.
4. Created a new list and added an item which is successful. But when tried attaching a document (or text or small file) it is unsuccessful.
Hence, I have concluded that there is no problem with SharePoint or any corruption of document library or list definition.
Looking at the event log carefully, I finally came to an idea that Antivirus is blocking something and it is where the problem is arising.

Solution:1. I have tried changing the Antivirus settings in the Central Administration 
2. Go to -> Central Administration -> Operations -> Antivirus -> Antivirus Settings -> I have unchecked the option Scan Documents on Upload -> Clicked save

3. Now, I have tried uploading the documents in the document library which is successful. Hence, concluding that the problem is due to the Microsoft Fore Front Security Antivirus.
4. Note: But we cannot make this option as default, since without antivirus scan, unwanted files (viruses, malwares, spywares, etc.,) may be uploaded which would be threat to the SharePoint environment.
5. Finally, updated the Antivirus definitions and license for the Fore Front antivirus. Then onwards, the upload is successful and secured one.

Microsoft Fore Front Security Antivirus1.  It is an antivirus provided by Microsoft dedicated to SharePoint environment. It will protect the SharePoint environment from the virus, spywares and other treats being uploaded.
2.  To know about the Microsoft Fore Front Security Antivirus click on this link

http://sharepoint.microsoft.com/en-us/product/Related-Technologies/Pages/Forefront-Protection-2010-for-SharePoint.aspx
3.  In the central Administration -> Operations -> Antivirus -> Antivirus Settings -> Scan documents on upload is set, then all the documents being uploaded will be scanned by the for front and then only uploaded into the SharePoint environment.

Happy Sharing!