If this is still ongoing then you may want to check your domain level group policy settings as there is a setting that prevents OU'S from blocking inheritance so basically even though you have the block inheritance setting ticked at the OU in question if the deny blocking inheritance is set at the domain level then the OU will have the domain level settings applied.
Re: Removing Computers from an OU
10 years 8 months ago #23684
Just a word of advice, if you're not using the Group Policy Management Console already, I highly recommend that you download it from the Microsoft site. It makes group policy management a breeze!
The original problem in the opening post, was it that you suspected computer objects were retaining settings configured in GPOs which were linked to former OUs where the object was situated?