Calculator.exe app opens on its own

[Persnipety]

It seems that in random times it will open kind of hidden in the background; i.e. not quite minimised to the taskbar but only the titlebar visible (with the minimise, maximise, and close buttons). It's annoying because I can't tell if it opens with certain program or time of day or what. Since I don't use it, is there a way to sort of lock down the process so it doesn't open on it's own?

 

[Patrick]

Maybe malware as its pretty popular for malware to abuse UAC EOP with calc.exe.

 

[Persnipety]

I've ran 3 different malware and spyware programs and a virus scan, but they didn't find anything. So (hopefully), it's not malware.