We have a customer that hosts our .NET application server on Windows Server 2003 x64. The problem is, its file sharing gets totally disabled after about 10-30 minutes. The only way to re-enable it is to restart the server but the same thing happens again after each restart. This server contains SQL Server 2005 Enterprise, .NET Framework 3.5 and our .NET based application server. We haven't had such a problem with any other customer before so we asked them to prepare another server to deploy our application on it. We installed our application server on the new machine and let SQL Server remain on the old one. Unfortunately the same problem happened to the new machine too. Now the old machine works only as database server and the new one works as application server but both of them have the same file sharing problem. File sharing on both machines doesn't get disabled on the same time but it eventually happens to both of them.
I wonder why is this happening and how to find the reason to this problem. Any suggestion or solution is much appreciated.