To extract the sponsor files, just run the setup and select to install the sponsor. You can grab the file in the Adverts directory of Program Files and do all the tests you want on it if you want.
A trojan is something that does things in your backs, uninvited, which is not the case of the sponsor program as you can see. Some antivirus companies just like scaring people to justify the presence of their software of their computers.
As for confirming that the sponsor may have been installed before, thank you
. You can confirm that by installing again without the sponsor program, you'll see that the sponsor exe won't be extracted automatically anymore. Here are the two keys that are verified to check for a previous sponsor installation from a previous version of Plus! :
SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\MsgPlus! Plugin - SponsorInstalled
SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\MessengerPlus3 - SponsorInstalled
If the value is set to 1, the new setup resets it to 0, extracts the new sponsor install/uninstall exe in the Adverts dir. This way, running the unisntaller of the new Plus! will allow uninstallation of the sponsor, if it was indeed installed (if not, then nothing special will happen, the sponsor's unisntaller will just be deleted).
I hope this helps you understand what happened in your case
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