I'm sorry it didn't work. In my experience I've heard of SD locking computers, but very few people complained about it. As you can imagine programs are coded to work with most machines although there might be the occasional one behaving differently. If I were you and wanted to investigate further, I would uninstall all security programs (including Sandboxie and key scrambler), install SD on a fairly clean Win7 and see if it still locks. If SD works on a clean system then I would install one by one all other security and see if there are any conflicts. Hopefully somebody else might have other ideas.