Google found out recently, they received some unusual search traffic. On investigating it further they realised that it was because of malware which infected computers, sends traffic to Google through a number of proxies.
To combat it, Google is proactively showing an alert to affected users (like the image below). This will warn users to connect carry out a system check and clean up, to make their computers safe.
What to do if your computer is infected?
If you see such an alert why looking up Google search page, make sure you update your anti-virus software and also run a scan to clean any infections.
Do drop in your comments.