If you can not rebuild your content permissions (rebuild does not finish or finishes with error) after installing Organic Groups (OG) access control module (part of the OG bundle) do this:
1. Run this command on your sql server:
delete from node_access;
insert into node_access values (0,0,'all',1,0,0);
2. Turn off the OG access control module
The module will be disabled but node permissions are will work and the site is not corrupted.
Update: May 29, 2009 by AlphaGeekBoy
In researching this issue and digging deeper, I found that I had two left-over content items from a content type that I had previously deleted. This was preventing the content permissions rebuild from rebuilding. Once, I removed those two nodes from the node and node_revisions table, I was able to leave OG Access control turned on and run rebuild permissions with no problem.
Content without a title can also cause this. Construct a view to check all your content for missing UID (UID=0), missing title, or missing type. There may be other things that can cause this, but those will definitely do it.