I am running Windows 2003, and do software development with IIS 6.0 as the Web server for local development on 127.0.0.1. That has worked for years, but maybe because of the Windows 2003 SP2 update, or some parallel Windows 2003 update, suddenly my local development environment does not work. This hurst when you are a software developer!
In addition, every time I try to use 127.0.0.1, it also kills the remote TCP/IP capability. I can make that remote capability work again by disabling then re-enabling the Local Adapter. Standard Internet access works fine, until the very first time I try to use 127.0.0.1, and then the remote Web access breaks immeidately, requiring the disable and enable sequence. I tried by deleting the network card from Device Manager and letting it re-detect, but no change occurred after all the dust settled.