After upgrading to 12.04 LTS, my desktop is now acting very strange with booting. Rebooting using the system "restart" option always works without any problem. Booting fresh (by pressing the power button) after a normal system "shutdown" within about 5-10 minutes works without any problem. But booting fresh after a normal system "shutdown" when the computer has been inactive for some longer time results in a hang before grub, before even the manufacturer's BIOS splash screen. I'm not sure exactly the time period required for this to happen, but I normally shut down the computer overnight. At first, I could get it to proceed after a hang by poking the tiny "reset" button under the power button, but that is now acting up, too, often requiring several tries before it works. I am worried that it will stop working altogether and/or I will harm something by using the hardware "reset" so often.
I had over 3 years of reliable behavior with this desktop using 10.04 LTS and never experienced anything like this.
Browsing the forums, I found a post similar to my problem that involved a faulty BIOS setting - something to do with trying to read the hard drives before they had fully spun up to speed. I did not change any BIOS settings when upgrading.
Is there something in the shutdown procedure that could be causing this to happen? I have tried to look at log files, but am inexperienced with that and cannot find any obvious error or warning messages.
My system: ---dual pentium E2180 CPU ---no nVidia or other proprietary drivers ---2.0GiB memory ---12.04 32-bit, kernel 3.2.0-38 (latest update, same problem with earlier 12.04 kernels) ---gnome 3.4.2 (using gnome metacity)