As the Windows 10 free upgrade period draws to a close, Microsoft is stepping up its operating system's nagware to full-screen takeovers. The Redmond software giant confirmed today it will start showing dark blue screens urging people to install the latest version of Windows. The full-screen ads will pop up on Windows 7 and 8.1 desktops from now until July 30, when the free upgrade period ends. "This notification is a reminder that the Window 10 free upgrade offer ends on July 29, 2016. Microsoft recommends that you upgrade to Windows 10 before the offer expires," Microsoft said. "You can...