Redmine

Please provide the information requested in SubmittingBugs, esp. the stack trace from the log file.

Btw, everything works when using hgweb.cgi, just not from redmine..

About your application's environment
Ruby version              1.8.7 (i386-mingw32)
RubyGems version          1.3.7
Rack version              1.0
Rails version             2.3.5
Active Record version     2.3.5
Active Resource version   2.3.5
Action Mailer version     2.3.5
Active Support version    2.3.5
Application root          E:/webserver/redmine
Environment               development
Database adapter          mysql
Database schema version   0

About your Redmine plugins
Redmine Graphs plugin   0.1.0

I'm using MySql 5.1.50
It's a clean install of redmine, no upgrade.

From production.log:

Processing RepositoriesController#entry (for 192.168.10.36 at 2010-11-17 09:12:09) [GET]
  Parameters: {"action"=>"entry", "id"=>"myproject", "path"=>[".hgignore"], "controller"=>"repositories"}
Rendering template within layouts/base
Completed in 1000ms (View: 47, DB: 16) | 500 Internal Server Error [http://myserver/projects/myproject/repository/entry/.hgignore]

Ok, some parts actually works...

Diff for a whole revision works. I'm able to see all the changes in each file. But viewing a file or diffs in a single file fails..

Do you use "file://" on Redmine setting?
Please see #3917.

No, just /pathto/repo.

Try full path on Windows such as "E:/pathto/repo".

How can I change this? The field is not editable.. Do I have to change it directly in the database?

You can delete repository with "Delete" button.
And re-add repository.

Great, thanks! That solved the problems.
I was a bit intimidated by the Delete button :) It's named delete, and links to destroy :)