Input devices not working at boot

[CBass2401]

Well, I'm not sure if this is caused by Ubuntu, but it started to happen after I installed Ubuntu, so I decided to ask here...

Sometimes, when I turn my PC it goes to Grub and I cannot use my keyboard to select an OS to boot (I have Ubuntu 13.04 and Windows 7 installed here), so it goes to the default OS, which is Windows 7. Once Windows starts, I can't use my mouse nor my keyboard, not even to turn my PC off (I have to do it from the Power Button)!

After turning my PC off and on again it goes back to normal, but still this happens to me about one out of five times I turn my PC on, any idea of what the cause might be? Thanks.

[2F4U]

In my opinion, this is not caused by Ubuntu. My guess would be that your USB devices draw more power than the USB ports are able to provide. I once had a mouse that did exactly that to a degree which sometimes prevented the machine to boot. If you have an external USB hub with a dedicated power supply, plug your devices into this USB hub and see if it helps.