由于系统缓冲区空间不足或队列已满，不能执行套接字上的操作。

这个是通过WebService上传文件的时候遇到的。webconfig配置的请求长度已配置到4E

Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SocketException (0x2747): 由于系统缓冲区空间不足或队列已满，不能执行套接字上的操作。]
System.Net.Sockets.Socket.MultipleSend(BufferOffsetSize[] buffers, SocketFlags socketFlags) +6224135
System.Net.Sockets.NetworkStream.MultipleWrite(BufferOffsetSize[] buffers) +62

[IOException: Unable to write data to the transport connection: 由于系统缓冲区空间不足或队列已满，不能执行套接字上的操作。.]
System.Net.Sockets.NetworkStream.MultipleWrite(BufferOffsetSize[] buffers) +234
System.Net.Connection.Write(ScatterGatherBuffers writeBuffer) +31
System.Net.ConnectStream.ResubmitWrite(ConnectStream oldStream, Boolean suppressWrite) +117

接收完成后，有没有把相应的资源给清理掉。

上次连接没close吧

建议你到专业论坛问问。