Recently I changed my machine and system (XP -> W7) and discovered that the scripts don't work anymore. The reason for that was the insufficient execution policy set in PowerShell by default. I changed it to the one previously used on my old machine and... no effect!
I started to think that the problem may not be caused by execution policy (although the error message was quite obvious) but then I found out there are actually 2 PowerShell versions installed: 64 a 32 bit. You can find them under "Windows PowerShell" folder in Accessories:
![2 versions of PowerShell in Windows 7](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhSSrLfrh0EVJIMTVzBjX3P2i9GFB6sL_2Ybv4TTeX8iYrCja4hcVR-0G-htCO4V43Os8eydAJ2r0znt39s-yKYDiGVt6JwbVfv0gWvEfHCl_1gX3Yo_l9KVqitTbYGdkbEFgxL6YixjE/s400/powershell.png)
Changing execution policy for both versions solved my problem.