Question : Sharepoint subsite permissions

I have a very strange problem that I have not encountered before with WSS 3.0.
This is a public site for individual clients so it is very critical that I get this resolved.
Layout of site is as follows, and for the example subsite names will also be the user name assigned access to that subsite. At no point should any subsite member be able to access the root site or anything other subsite of Home.

Root site is called Home: my domain user is the site owner and has full control.
Home\SiteA: my user has full control and user SiteA has “read Only”
Home\SiteB: my user has full control and user SiteB has “read Only”
Home\SiteC: my user has full control and user SiteC has “read Only”
What is happening is if I modify SiteC those changes affect SiteB&A and Home. I came across this because I got a call from a user on SiteA that they could not access their site, I looked at the permissions and the last changes I made to SiteC were now set for SiteA (and after checking siteB).
Testing I found that if I remove all users (not my domain user) from siteA, all users are removed from all sites including Home. If I go into siteA and add the SiteA user SiteA user is then added to Home and SiteB&C.
I know that when you create a subsite it asks if you want to use the site of the parent or unique permissions. Obviously it seems that I might have left “Parent” though I am pretty sure that I did not and that I did select “unique”.  To test that I just created a new sub SiteD and made certain I selected Unique permissions. I added SiteC read only to SiteD, then looked at siteB and siteC user was listed there, I removed the user and then looked at the newly created SiteD permissions and SiteC user was gone. So with that I do not believe that it was me selecting the incorrect setting when creating the site.
(I hope you can follow that)
What I need to know is what is going wrong so I can stop this in the future and how to rectify the issue now. I have looked online but have come up with nothing.

Does anyone know what the _____ I did wrong?

Thank you for any help.
Richard

Answer : Sharepoint subsite permissions

oh ok.  well you are using the same group on both sites, so if you remove a user from one site it will remove from the other (since its the same group).  a site collection has common user groups that can be used in all it's subsites.  if i were you i would create SharePoint groups for each subsite (SiteA Visitors, Site A Contributors, Site A Owners, Site B Visitors, Site B Contributors, ect).  Add these groups to their respected subsites and give them correct permissions (do this under the site permissions link).  Then you will have groups dedicated to each subsite instead of using the same groups for all.