I had a spell earlier in the year with Acer desktops being sent to me with some problems,this turned out to be the Mouse and one particular machine...the keyboard.
A simple replacement was the key to the fix.
I recently dealt with a Dell (new machine) that i recommended and built online for a friend.
happy computing for a month or two,then that dreaded phone call...it wont work,its freezing at post bios screen.
Simple remedy was to remove the keyboard,shut down via the start button and plug in the keyboard and reboot,job done and no damage or lost data or settings.
I learnt a lot earlier in the year with those Acers failing to boot,i had stripped one down to nothing left,tried new ram/mobo/psu etc...still no luck...this one turned out to have a dual bios,once cleared on both sets of pins...bingo all was well.