Windows 7 currently powers around 55 per cent of the world's computers – but use it "at your own risk, at your own peril," Microsoft has warned.
The controversial comments about the hugely popular operating system, which was first released in October 2009, were made by Microsoft chief marketing officer Chris Capossela.
Mr Capossela issued the warning during his appearance on Windows Weekly – an online show on the TWiT podcast network.
The chief marketing officer for Microsoft made the comment while fielding questions about Windows 10 and the firm's upgrade tactics.
"As we've moved Windows to a service, we're trying to find the right balance," Mr Capossela told Windows Weekly host Leo Laporte.
"It's just so incredibly important to try and end the fragmentation of the Windows install base.
"And so we think that every machine that's capable of running Windows 10, we should be doing everything we possibly can to get people to move to Windows 10.
"We do worry when people are running an operating system that's 10 years old that the next printer they buy isn’t going to work well, or they buy a new game, they buy Fallout 4, a very popular game, and it doesn’t work on a bunch of older machine.
"As we're pushing our hardware partners to build great new stuff that takes advantage of Windows 10, that obviously makes the old stuff really bad, and not to mention viruses and security problems.
"So we really are trying to push people to get to Windows 10."
It's easy to understand why Microsoft is keen to push users to its latest operating system, Windows 10.
But the Redmond technology firm has already confirmed it will continue to support Windows 7 until 2020, which means the operating system will remain up-to-date with the latest security patches.
Microsoft first launched its hugely popular Windows 7 operating system back in October 2009
As a result, the "viruses and security problems" highlighted by Mr Capossela will not become an issue until 2020.
His example of Fallout 4 not running on Windows 7 machines is also not true. The blockbuster video game is fully compatible with Windows 7 and Windows 8.
If you're having issues getting this game to load, you need to update the components in your PC – not your operating system.
Microsoft has previously announced it would like one billion devices to run on Windows 10 within two to three years of its release.
The US technology firm released its new operating system – Windows 10 – back in July.
The redesigned operating system was the first to unite all Windows-powered devices – from sprawling desktop set-ups to svelte smartphones, tablets, Raspberry Pis and even the firm's own Xbox One video game console.
Microsoft announced that Windows 10 would be a free upgrade for anyone running genuine copies of Windows 7 or Windows 8.
However this offer expires on the first year anniversary of the release of the new operating system.
Perhaps spurred on by the end of the upgrade offer, more than 200 million people have upgraded to the latest operating system.