Customer has a big suspicion that his system was infected with viruses. After a thorough investigation and looking into the systems files with tools such as malwarebytes and spyware Doctor. Plus the usage of Avast anti-virus, we have not found any traces. So we started to look further into the claims. And we found an Opt-in Adware chrome extension that was installed with freeware that was the culprit. The extension was removed and we tested the machine and there was no popups.