I was install CMS bitrix for my site. But we have problems with 404.php. Maybe somebody can help us? I'm very sad. This web hosting does not support right CMS bitrix. I think I have to change hosting.
From looking at the requirements, I don't see any reason it won't run on DreamHost. As it is a commercial product, have you contacted the publisher for support?
I do recommend you to contact Bitrix Helpdesk (www.bitrixsoft.com).They will help you to diagnose this problem.Please provide them temporary access to your site.
Bitrix is going to launch its 7.0 version. Ive played around with it and it is amazing - really. They have an invitation out there for an online demo of their Bitrix Virtual Lab: http://www.bitrixsoft.com/sitemanager/demo.php. It is worth dropping by to look at the functionality they have added.