The intrusion attempt went to almost 600 around next 3 hours. Then I observed the details of target of intrusion.I found all these were targeted to some folder called port Locker.I was little bit concerned about the issue and approached college authorities.They thoroughly checked system and found that there had been a malicious software called as 'hotspot', which in turns sucks the entire band width of wifi and can be manipulated very easily.So GB size can never be an issue.
Looking into wikipedia, i understood of what hotspot is "A 'poisoned/rogue hotspot' refers to a free public hotspot set up by identity thieves or other malicious individuals for the purpose of "sniffing" the data sent by the user. Such identity thieves will have access to the MAC address of the connecting terminal, which individually identifies the hardware. By examining packets sent, they may attempt to decipher passwords, login names, or other sensitive information."
Further due to thorough analysis, i found lots of unwanted applications and add-ons like yontoo, which was detected as suspicious by my anti-virus. It took a good change on my system and its performance after most of these applications were once removed.
So be aware of such identity thieves around you,even in your same LAN/Wifi and do try the level best to get rid of issues like this. What i found myself to be secure afterwards was,having a good firewall and mechanism to detect the intrusions will always give you an upper hand in being betrayed by these poisoned hotspots in your personal computer/laptops.