Having done some upgrades to my server (PHP, apache) I noticed I was getting some odd errors in the apache log and one of my PHP based sites wasn’t loading. The error in the log was:
[Sun Sep 05 20:23:40 2010] [error] [client X.X.X.X] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.
Now having done some digging everything suggested the rewrite rule was wrong, or, behaving differently after the upgrade but it turned out that the problem was in fact PHP short_open_tag related. My php.ini had short_open_tag = Off (which it should, but the site in question was a quick one). Changing that to On and giving apache a restart made the problem go away. When I get a chance I will make the <? tags <?php but it’s not a biggy right now. For more on short_open_tag check the manual.