Windows XP menu ‘Add mirror’ greyed out

Today I was trying to make a software RAID 1 in Windows XP Professional. I thought I have done that a couple times, but today somehow menu Add mirror stayed inactive.

I did a google search and to my surprise two KB articles from Microsoft support came out.

They both have the following paragraph:

You cannot create mirrored volumes on computers that are running Windows XP Home Edition, Windows XP Professional or Windows XP 64-Bit Edition. However, you can use a computer that is running Windows XP Professional to create mirrored volumes on remote computers that are running Windows 2000 Server, Windows 2000 Advanced Server, or Windows 2000 Datacenter Server. You must have administrative privileges on the remote computer to do this.

So how it is possible, that I have created such volumes in the past? Perhaps in Windows Server or in my dreams.

Also, there is a known hack that involves changing system files with a hex editor, but this is one of my production machines, so I will not take a risk, and I would not recommend this hack to anyone. Use the following link on your own risk (I warned you): How to enable software RAID 1 in Windows XP (hack).