Why does login invoke PC Guard

I am having a problem with 2 new installations of WordPress. Every time I try to log in as admin, I get a 10 second countdown where I am told – I am there because of PC Guard. Then after this 10 second delay, a captcha / recaptcha screen which presents me with up to approx 10 screens of cycles, busses, cars, crosswalks, motorbikes, taxis, steps, stairs, fire hydrants and bridges – before I can get in – and it is pretty annoying. Any way I can remove this facility. I don’t have any plugins installed and cant see any PC Guard or recapture settings and I’ve never encountered it before on previous WordPress installations.