It started one day, suddenly. When I wanted to search something via Google, there was a captcha figure to rewrite and below it, there was written: Our systems have detected unusual traffic from your computer network. This page checks to see if it's really you sending the requests, and not a robot. ... This problem was appearing only on Mozilla Firefox. On Internet Explorer and Google Chrome - not. I told it to my friend, he cleaned some registers on my pc (I don't know what is it) and then the problem disappeared for few days but it now appears again. Sometimes it's ok and I can use Google search usually, but sometimes the problem is happening. At home, we have 3 computers, all are connected to internet by wires (no wifi) to our internet provider, who also provides internet to many other people. Once happened that the problem was appearing on 2 computers (mine too) in all browsers. On the 3rd computer the problem was not. (I don't send any files from my computer to the others.) Sometimes, very often, the problem appears on all 3 computers in all browsers but only when I type an asterisk ( * ) to Google search. But mostly, the problem is only on my computer and only in Mozilla Firefox. Reinstalling Mozilla doesn't help. I have scanned my computer for viruses via Avast anivirus (installed on my pc) and Eset antivirus (online scan), but no virus was found. I know that the problem may come from another computer from our internet provider's network, but what if not? What if it all comes from mine? How can I find it out? How can I solve all this troubles? Thank You for answering.