Spyware Detective? There was a rogue anti-virus software package named Spyware Detective. Rogue anti-virus software packages are actually trojan horse programs; you’re encouraged to install it for some reason when there is actually a malicious payload.
I would guess that installing Spyware Detective is causing your problems.
Meanwhile … anti-virus vendors will not claim compatibility with other anti-virus products. Of course they will ask you to uninstall other anti-virus products. There is no specific, significant problem with more than one product. There is no specific, significant benefit either.
Before installing that next package you download, upload it to VirusTotal and see what a multitude of anti-virus vendors think about it.
For years I have been using Avast. That alongwith regular windows updates has so far kept me safe. And Avast has a smaller footprint, much smaller compared to Symantec or McAfee