The patch link I entered into this article was wrong or is no longer active--I've replaced it below, so if you're having trouble, try the new link instead. BTW: The error I'm describing here seems to only affect Zen themes--at least those are the only sites where I've seen this happen. I think that Zen is prone to this error because it uses so many style sheets -- not totally sure about that but, Zen is a real hassle to develop for in any case, especially when it comes to developing for IE. Now I know that a lot of people use Zen without incident, but come on--isn't it time to at least consider switching to Blueprint? I'm telling you, it's soooooo much easier.

After a recent server upgrade at Pair Networks, several Drupal sites we host there began to experience unexpected behavior – specifically the dreaded White Screen of Death.

There's a well document series of steps to follow during WSOD troubleshooting–Drupal's reference page (http://drupal.org/node/158043) tends to provide the answer in most cases. But this time, it was something entirely different. The usual suspects weren't even in the same neighborhood. (Memory: fine; htaccess: fine; Cache Tables: clear; DB: great. Modules: nothing to report.)

We were running the latest round of Drupal 6 (at the time of this writing, D6.14), but hadn't changed anything or added any new modules. One interesting clue: When CSS optimization was turned off, the sites functioned fine.

Enter the D6 common patch found at http://drupal.org/node/444228 . As it turns out some code needed for ie mac 5 was causing the problem. This code causes an error on FreeBSD 7.1-RELEASE-p4. Good God.

Anyway, this patch http://d6.drupal.org/files/issues/common.inc-56-d6.patch solved the issue on every site I've found it on. (Try this instead http://drupal.org/files/issues/common.inc-56-d6.patch ) Basically, it replaces a regex pattern that chokes Drupal during css compression. I think that this particular patch isn't perfect, because there has been some modifications in the discussion group, but it works for me. And considering that I haven't seen an IE mac 5 visit on any site I've run in the last two years, I'm just fine with it.