I came across a nice article at forum.openerp.com/forum/topic36094.html

When I executed all the scripts, I got permissions denied error for most of them. An example of that error is

Traceback (most recent call last):
  File "/usr/bin/openerp-server", line 4, in <module>
    import pkg_resources
  File "/usr/lib/python2.6/site-packages/pkg_resources.py", line 2655, in <module>
    working_set.require(__requires__)
  File "/usr/lib/python2.6/site-packages/pkg_resources.py", line 648, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.6/site-packages/pkg_resources.py", line 546, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: gevent

I recently installed openerp on a ubuntu server without any problems.