When the groundhog saw his shadow last month, it wasn't a signal of an early spring but a hint that Windows would have one of those upside-down stretches.Violating the cardinal rule of newer Windows editions, Windows 10 dropped the most user share since March 2018, making for a confusing picture about how customers' migrations are proceeding.

Meanwhile, the already-supplanted Windows 7 added share to its total last month, erasing more than half of the end-of-the-year dramatic decline that at the time seemed to show a quickening pace toward its retirement.[ Related: How to clean up your Windows 10 act ]According to web analytics vendor Net Applications, Windows 10's share fell by six-tenths of a percentage point in February, ending the month at 40.3% of all personal computers and 46.1% of all PCs running Windows.

(The second number is always larger than the first because Windows does not power all personal computers; in February, Windows ran 87% of the world's machines.

All but a small fraction of the rest ran macOS, Linux or Chrome OS.)