I have the exact same issue.
In fact, i can take the discussion a step further.
I installed Redmine via the instructions here: http://wiki.dreamhost.com/Redmine
Once installed the application gave me the Pipe issue mentioned above. I reloaded the page and after a 10s wait time the page loaded and i was able to start filling things out. The problem is that each page i load, the first time, and if i am not logged in already each successive page further into the app lands on an an Internal Server Error page, with a different stack trace. This happens on every single page, and intermittently after the initial load i have to deal with the same error coming back.
By and large i think the application is in an unusable state, as i cant expect my developers to be able to use an application isnt stable enough to do anything. I did check the code out from their stable 1.1 tagged release and in dealing with having to load the pages more than 2 times i have gotten it to at least "work" properly.[hr]
I did find this:
If you get an error message mentioning a broken pipe with the exception class PhusionPassenger::Railz::ApplicationSpawner::Error as depicted in the image to the right, then you're most likely running into memory limit problems. Basically, what's happening is the request being processed by Passenger caused your user memory limit on the server to be exceeded and the Rails process that was handling that request was killed. If you're seeing this error, then it's usually a dead giveaway that this is happening. Unfortunately, there isn't a whole lot that can be done about this since even a very basic standard Rails application requires a lot of memory up front. In fact, enough memory to hit your memory limit almost immediately -- especially if you have other websites being hosted on your account. This will happen even more frequently if you have more than one Rails application being hosted from the same account. The best way to ensure that you don't run into this problem is to move your Rails sites over to a DreamHost PS. That will give you guaranteed, scalable memory that you can adjust until your memory needs are met.
Which i can understand, but why would reloading work out?