I have ordered two licenses of PC-Doctor for Windows - one on Jan 22, '16 (order PCD160108-5623-14108) and one on Feb 23, '16 (order PCD160223-3231-12180). I installed the ... 14108 copy on my primary desktop but a few days later reinstalled it on my secondary desktop under the same email activation process as I followed when I initially installed it on my primary desktop. Yesterday, I attempted to install the ... 12180 copy on my primary desktop (i.e., the one on which the ... 14108 copy was initially installed); however, I received an error code when I launched the product - i.e., "Your system configuration has changed too many times ... (Error 4)". I need your help in resolving the issue please. Net-net is that I have purchased two copies of the product - one for each of two pc's (primary and secondary) - and need for each of them to be activated. The ... 14108 copy is running fine on my secondary desktop but now I need the ... 12180 copy activated for my primary desktop. And by the way, before I attempted to load the ... 12180 version on my primary desktop, I uninstalled the ... 14108 version but that didn't help. Sorry if this post is confusing but it's the best I could do! Thx.