Windows 7 insomnia after Ubuntu installation

Recently, I installed Ubuntu 13.04 on my Windows 7 machine. It all went smooth, and was even surprised how everything seemed to work well in Ubuntu without any tweaking. The collateral damage was on the Windows side: it could not go to stand-by any more, even if it was no problem before I installed Ubuntu.

A short search showed an interesting thread from the Ubuntu forum. The various solutions requiring activating a partition were not helpful to me, since the installation was on two separate disks, both active partitions. However, the powercfg command did the trick:

powercfg -h off as administrator restaured instantly my stand-by :)