Malware:A generic name for all types of malicious programs: adware, backdoors, rogues, trojans, viruses and worms.
Antivirus System Pro alert is typical fabricated security message. AntivirusSystem Pro loads several falsified alerts to make an impression of badly infected computer. The main purpose of such alerts is tricking people into buying AntivirusSystemPro as it was a useful program.
The trojan reported by Antivirus System Pro is not even a real thing. Win32/Nuqel.E is just a name made up by scammers to intimidate victims. If you receive the alert, remove Antivirus System Pro as soon as possible.
Technical details (How to remove Antivirus System Pro alert(pop up))