At AppTheory we use SharePoint 2007 to track all ongoing projects for clients.  As I mentioned in a previous post there are times when we want to open these sites up to clients.  We open these sites up to our clients through forms based authentication.  Recently I experienced a problem with giving access to a site for a SharePoint group consisting of FBA users.  Our site structure consists of:

Sites B and C needed to  be open to The SharePoint Group containing the FBA users.  I was able to open access to the FBA group to Site B but was not able to inherit permissions from site B to site C.  This is the first time I had encountered this problem.  Every time I would try to access site C with the FBA accounts I would get an access denied. My first thought was to retrace my steps and make sure I had given the correct access for the group that contained these accounts.  After making sure that the accounts were in the right group and that the group had the correct rights for the site I decided to use Sysinternals  Process Monitor (http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx.) Process Monitor is a great tool for determining what is accessing a file and the response when that file is being accessed.  I created a filter to look for processes attached to SharePoint and could find no access denied results.   

I was stumped so I created a test structure from a backup of the sites.  I was able to provide access to the SharePoint Group and all accounts were able to access the test sites.  After a few hours of frustration I decided to delete the active sites and restore from the backup.  I applied the permissions for FBA group and was able to access the sites with no problem.  I am still at a loss for the cause of the problem but I am glad to know that a restore of the sites fixed the problem.