Socket Error 10055 - No Buffer Space Available

Error 10055 means that Windows has run out of TCP/IP socket buffers because too many connections are open at once.

Things to check if this happens are:

Current versions of Windows can support many thousands of IP connections at once. Server versions can support more than desktop versions if you have a busy server, so it is unlikely that VPOP3 on its own will deplete the socket buffers, and the problem is usually some other software.