Sorry for late reply! Uhh… You mentioning “black screen instead of the green tick it always show, on the gadget only the twitter, facebook and blog icon could be press”. Since I am not a IT expert I will give you the best explanation I have since I faced that similar kind of issue when I had avast 8 now I have avast 9. Sometimes antivirus software doesn’t start up properly or windows security center can’t report that an antivirus software is installed. Back when I had avast 8, it sometimes shuts down itself for some reason I don’t know and I clicked on start all shields nothing happened but within 2 minutes everything came back to normal.
About your internet connection, all i can say is that shut down your modem and wait for 2-4 minutes and turn the modem back on. I don’t think there’s any problem that can be related between internet connection and avast. Having bad internet connection makes avast cause issues not having the latest vps updates and streaming updates.
That’s the best explanation I can give you. I hope it can help you.
If you are worried about malware infections. Download SuperAntiSpyware and Malwarebytes Antimalware. Update them both. Run both of them in Safe mode. Do the same for avast.