Well OK, not mysterious, and not really hidden. And I did cause it, but since I had forgotten what I did, I had a hard time finding it.
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings] "MigrateProxy"=dword:00000001 "ProxyEnable"=dword:00000001 "ProxyHttp1.1"=dword:00000000 "ProxyServer"="http://ProxyServername:80" "ProxyOverride"="<local>"http://support.microsoft.com/kb/819961 I was trying to find a way to modify these settings from the command line, and include it as part of my “fix_routing” script (which needs a write-up). So I tried some stuff, and it didn’t work, and I gave up and moved on.
C:\Documents and Settings\aujaha>proxycfg Microsoft (R) WinHTTP Default Proxy Configuration Tool Copyright (c) Microsoft Corporation. All rights reserved. Current WinHTTP proxy settings under: HKEY_LOCAL_MACHINE\ SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Connections\ WinHttpSettings : Proxy Server(s) : 10.10.0.229:8080 Bypass List : *.local;*.big.corp;10.10.*;<local>
I zeroed out this key, and things seem to be working again.