ArgumentError (invalid date) on redmine

Question

Have installed redmine on ubuntu 10.04 LTS but when I add quotes or comments to an issue I get this error:

ArgumentError (invalid date):
  /usr/local/lib/ruby/1.8/date.rb:752:in `civil'
    /app/models/time_entry.rb:66:in `spent_on='

a few more lines under those