Samsung device security has been scanning my device since yesterday

[Lookdownthesofa]

Yesterday I had a message pop up on my Samsung S5 Neo screen saying that a threat had been detected on my phone.

I went into SmartManager and clicked the security icon and it started to scan my phone. It froze after a while, so I restarted the scan.

It has now been 'scanning' for about 20 hours. Or rather, the icon is spinning round and there is a constant message on my home screen saying 'device security - scanning device for threats'.

Now, I expect the thing has just frozen again and it hasn't really been scanning my device for this long but how can I make it stop?? I have tried turning phone off and on again but it is still spinning/msg still there.

Settings > Applications > Application Manager.
View running apps, tap to stop.

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Thanks Finn.

Unfortunately, whenever I try to access Application Manager as you explained above I get a pop up saying "Unfortunately, Settings has stopped", so I can't get into application manager at all.

I've also had messages in the last month or so (before the threat was detected) saying "Unfortunately Touchwiz/touchwiz home has stopped". And just now a pop up saying "Unfortunately Google Apps have stopped".

Some googling suggests that a factory reset might be in order. I've only had this phone about two months though, so very annoying. Are there any other fixes other than a factory reset? What can be causing all these error messages?