|It sounds to me like you have malware on your system, especially with what you said in point 2. I suggest you download and install Malwarebytes' Anti-malware Free, update all available definitions, and do a full system scan. Clean all infections and scan again until it reports none. If there are persistent problems, report back.|
Afterward, do the same steps with SUPERAntispyware Free. SAS also detects and removes browser tracking cookies which aren't necessarily malicious but a good thing to remove. Don't be alarmed if it reports a load of problems that turn out to be tracking cookies.
Afterward, scan with Avast, your real-time protection and report the results. I personally don't like Avast Free and prefer Avira Free or even AVG Free to better initially protect against threats. The latter seems to slow some computers down, however.
Apologies if I don't respond to your reply immediately. I don't check this site daily, but you're welcome to PM me as a reminder.