Microsoft has admitted that Windows Genuine Advantage (WGA) will phone Redmond every day - something it neglected to tell users before they installed it.

WGA is designed to detect pirated copies of MS software but is also creating some false positives - two UK dealers have contacted the Reg to report customers complaining that WGA had branded their software as an illegal copy.

The software checks what is installed on your machine and then reports back to Microsoft - it sends your IP number and information on your software set-up. If your software is dodgy you will start receiving pop-up reminders from Microsoft.

Michaela Alexander, head of anti-piracy at Microsoft UK, told the Reg: “First of all this is a pilot - customers have the choice to subscribe or not. WGA is very careful about which license keys are checked - some numbers have been leaked and therefore have been culled by Microsoft. If customers bought a genuine copy of Windows but as a result of a poor installation or a repair a different license key was used then WGA would flag it as not genuine.”