Here is a strange one I have not run across before.

My Acer Aspire laptop is a dual boot Win7/Ubuntu, typically booting into Ubuntu.

Occasionally, it will not boot. I mean, I don't even get to the screen where I could choose a different operating system. So, for some strange reason, if I unplug the power cord, and boot from battery, it will get me to the OS choice screen, but it won't boot automatically. That's OK, because I choose 'recover' anyways.

My confusion is that this is very intermittent, and I have no idea what causes it.

Any guru's who may have any idea what is happening? My computer is updated with the latest updates at all times.