The fear is that customers will put off buying a PC until next year when Windows 8 hits the shops.
Microsoft said it will defer the $450 million to $550 million of revenue it expects to generate this quarter from an offer to upgrade to its new Windows 8 operating system.
According to Reuters, Vole is offering customers who buy qualifying Windows 7 PCs the option to download an upgrade to Windows 8 Pro for about $14.99, or $15 as we call it.
The company said it would recognise the revenue from the offer when consumers actually upgrade or on February 28, when the programme expires.
Windows 8 is expected to kick start the PC market and will provide Microsoft with almost half of its profit, Microsoft hopes.
Microsoft's shareholders did not like the idea. The company's shares were down by 37 cents on the back of the announcement.