Sometimes if you have troubles installing any other AV programs , it could be due to the malware or trojan that are on the pc...

- Only have 1 AV program is installed at a time & only 1 running at a time or it might mess up the new AV install - may "see" the new one as a virus..

If you don't have anything important saved on the pc I'd format & reinstall your OS - or you might be going in circles until the bad actor is totally gone..

You can save your bookmarks and any photos or emails /documents to a flash drive to add them back on the fresh system..