I've encountered a bug which has surfaced in Windows 7 when using MSE (Microsoft security essentials) and an external USB HD, in my case Maxtor OneTouch 4. I noticed that the external HD is flashing all the time as it does when it's being accessed and so it was unable to enter "power saving mode" by going to "sleep". I have traced the culprit to MSE and "real time protection". If I stop the service then the drive stops flashing and power saving mode can kick in, restart the RTP and the drive starts up again. I have tried excluding the drive in MSE settings "excluded files and locations" but this hasn't made one tat worth of difference. Anyone have any ideas how to solve this issue before I uninstall MSE and use another AV product? 