Fills From Left To Right With The Blue Line: Error Message 0x800CCC13

I get the words "Authorizing" and "Checking Mail" down near my clock, and I get the little window with the "receiving messages" line, that fills from left to right with the blue line; but then, after the blue line is all the way across, there's a long delay, and I get a window with an error message with the number 0x800CCC13. When I look that error message up on the Microsoft site, it says that means:

0x800CCC13 IXP_E_SOCKET_WRITE_ERROR Unable to read Winsock reply

Interestingly, even though the new messages don't come in, everything else works fine. All the menus and functions are A-OK. I can still compose new messages or replies to earlier messages, and send them out, and they go out just fine. But then, after the new compositions are sent, the program automatically tries to bring in (receive) new messages, and sometimes it succeeds, but sometimes it just runs into the same error message. I've contacted my server and they claim that there is nothing wrong at their end. They think it is a flaw in my Windows Mail program. (On my computer upstairs, which has a later version of Vista and Windows Mail by about one year, Windows Mail works fine.) I've considered the following options:

1. Use System Restore to go back a few months, and see if that puts Windows Mail back to normal.

2. Try to download a new Windows Mail program compatible with my version of Vista (if it's possible to download Windows Mail separately).

I'm worried that if I use the second option it will wipe out all my mail,
which is too important for me to lose.