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."

But Alexander said all this was detailed in the opt-in process. But she added: "The last thing we want is unhappy customers so we are investigating this - but it is a pilot and this is part of the process."

The word from the US is that Microsoft will change WGA so it only phones home once a fortnight, instead of every day, and will do a better job of letting users know what the software is doing. More from Seattle Post Intelligencer here.

One of the dealers with the original problem emailed us the following:

The problem was caused by an active-x control being blocked by IE security. The fix was to go to http://www.microsoft.com/genuine/diag and following instructions. This runs through a series of checks to ensure that the validation process can operate correctly, then advises of the necessary changes in IE setup to permit correct validation. In the case of our clients, the problem was correctly diagnosed and the resolution worked fine.

It's just alarming that for a simple security problem, Microsoft had informed the end user (by way of a message displayed on their screen) that they might be [quote] "The victim of software  counterfeiting".