I have btnetprotect plus installed on my computer and about 1 hour ago the security tool virus/trojan appeared on my computer, i removed it using system restore, but my question is should it have not been picked up beforehand
I just checked, and BT Net Protect Plus is the standard McAfee Home & Home Office package.
This question has been asked before, and the answer is that Security Tool is neither a virus nor a Trojan. To McAfee (and many other AV programs) it appears as just another program. It has a few distinctive characteristics which I think McAfee should be modified to recognise, but it is mainly a nuisance and a scam. It's just a fake program trying to part you from your money.
You have probably got rid of it if you went back to a previous system restore point, but you might want to read the information in the link below -