I have a site that uses SEF URLs and htaccess RewriteRules to serve up the pages. This has worked fine for several years until the arrival of IE9.

Now it appears that the links are not being rewritten and the site is dead in the water.

I have tried different compatabilty modes, to no avail, and I've played with the Rewrite Rules over and over, tried different doctypes and a few other browser settings. I agree that it cannot in theory be a browser specific problem if the problem is with the htaccess file but this site works in IE8, firefox and chrome. I have run the rewriterule through a validator and it looks fine. Any ideas would be appreciated as I am running out of ideas.

The site is www.marlboroughsounds.co.nz a sample link is

http://www.marlboroughsounds.co.nz/walking/freedom-walk-queen-charlotte-track/4dfw

and the rewrite rule thats not working looks like this:

RewriteRule ^walking/.*/([a-z0-9_]*)/?$ /walking.php?act_code=$1 [L]

The link fails and it serves up a browser 404 page, not even the custom 404 I have for the site.

Any ideas would be much appreciated as I am stumped.