We've had some issues with this, but until now, could not nail down for certain what was occurring. This issue occurs about 50% of the time during the process that I will describe.

Specs:

• PHP 5.5.4 (bundled ZendOpcache)
• IIS 7.5 Server 2008 x64
• opcache.revalidate_freq=15

1. I tried to deploy our site (we use a robocopy script after tagging and checking out with Git), it's a large site, but the issue seems to always be with composer files (specifically with the autoload.php file, but not 100% that is always the file)
2. After deployment, the site will not load (blank page)
3. FastCGI log showed this on every request: 1.[02-Oct-2013 02:38:31 America/Chicago] PHP Fatal error: Class 'ComposerAutoloaderInita8d874c72e26eea58cb1ad4a2bfaaf31' not found in C:\inetpub\wwwroot\vendor\autoload.php on line 7
4. That error is correct, the class ''ComposerAutoloaderInita8d874c72e26eea58cb1ad4a2bfaaf31' does not exist anymore
5. I checked and there was not physical file with that call being made, that was the previous autoloader created by composer
6. I ran opcache_reset() and the file refreshed and the site loaded