"Process imap not running" error message

[Sarir Khamsi]

I recently downloaded GNU Emacs 21.3.50.1 (NT) and occasionally get
the message above when I try to retrieve mail (via imap, as you might
guess). I'm on WinXP, SP1 and GNus 5.10.6. The stack trace is as follows:

,----
| Debugger entered--Lisp error: (error "Process imap not running")
|   process-send-string(#<process imap> "421 UID SEARCH SEEN
\n")
|   imap-send-command-1("421 UID SEARCH SEEN")
|   imap-send-command("UID SEARCH SEEN" nil)
|   imap-send-command-wait("UID SEARCH SEEN")
|   imap-search("SEEN")
|   nnimap-request-update-info-internal("mail.raytheon" 
("nnimap+mailserver.com:mail.raytheon" 1 ((1 . 1974)) ((tick 1737 1742 1744 
1746 1748 1750 1769 1785 1801 1837 1856 1872 1885 1887 1891 ... 1924 1927 1932 
... ... 1961 1964 ... ...) (reply 1725 ... 1733 1738 1744 ... ... 1754 1756 
1766 1769 1778 1801 1804 1811 1824 1836 1842 1844 1856 1871 ... 1891 ... 1930 
1952 ... 1973) (seen ... ... ... ... ... ... ... ... 873 ... ... ... ... ... 
... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) 
(forward 12 211 373 428 452 466 493 550 858 907 936 1238 1384 1474 1529 1650 
1694 1746 1769) (download 1020) (cache 2 11 16 18 ... 32 35 42 51 72 76 78 ... 
101 114 132 ... 147 155 159 ... 185 ... ... 194 196 198 200 204 216 229 237 240 
244 277 ... 300 320 ... ... 337 340 347 351 354 360 366 372 ... ...) (save 569 
612 675 855 907 929 ... 965 986 996 1005 1013 1033 1039 1041 1056 1084 1131 
1137 1152 1157 1214 1238 1279 1361 1406 1417 1424 1437 1445 1449 1452 1455 1494 
... 1529 1555 1618 1641 ... ... 1666 1682 1684 1724 1726 1733 1769 1802 ...)) 
(nnimap "mailserver.com") ((uidvalidity . "34"))) "mailserver.com")
|   nnimap-request-group("mail.raytheon" "mailserver.com" nil)
|   gnus-activate-group("nnimap+mailserver.com:mail.raytheon" scan)
|   gnus-get-unread-articles(1)
|   gnus-group-get-new-news(1)
|   call-interactively(gnus-group-get-new-news)
`----

If I re-run the command to get mail, or restart Gnus, it seems to
work. Any ideas? Thanks.

Sarir