According to several reports, a rare error of Local Disk drive partitions has a red circle with an X in their icons. The cause of this error is still unknown, but it ...

Check if the battery icon shows a red cross. Sometimes ... You can use the built-in Power Efficiency Diagnostic Report Tool, a command-line utility that generates a report on your laptop battery ...

The small tweak meant that when you opened the notification shade on your phone, Gmail's icon was no longer red like before, making your unread emails stand out less among your unopened alerts.