I've just realised a weird behaviour regarding Windows Defender in my laptop. Whenever I open (run) it, either by prompting to run a scan or just to open the GUI, it always closes itself immediately (even before it finishes scanning my computer if I open it to scan my computer, i.e. I cannot do a thing with it closing in less than 2 seconds). This weird behaviour stops for just once before I restarted my laptop but then it reappears. Strangely to me, this issue doesn't come up if I run Windows Defender as Administrator (it ran just normally without closing by itself); however, I'm just worried if this issue had anything to do with virus, spyware, or malware.
Can anyone suggest me what I should do? I'm running a genuine (and activated) copy of Windows 7 Home Basic. Many thanks in advance