I've been running a 'localhost' Apache server on my Win7 machines (and previously on WinXP) for several years. I mainly use Firefox as my development browser, but of course I have to be able to test with others, particularly IE.
Recently, on one of my computers, for no obvious reason, IE9 is unable to 'see' the localhost files. If I try to load one the screen remains blank and the 'spinner' on the tab just goes round for ever. It's not the files themselves, because if I upload to a remote server they will load as usual. I'm not aware of having had this problem before. The same thing is happening with Safari, but not Opera. I've just reinstalled Opera, so perhaps it's worth trying the same with the other two.
Could there be something I've overlooked in the setting up of my Apache server ? Or (more likely) something I've inadvertently changed.