Problems again with my desktop

This desktop PC motherboard was changed several months ago. Regrettably the problem seems to be returning. Often the mouse and keyboard would be frozen on start up and I have to hard reboot it. It has the same symptoms as previous to the motherboard replacement. The PC can be switched off but the LED light on the USB hard disc remains on.

I have tried disconnecting the ext hard disc before powering up the machine. Doesn't always work. This time I tried something more drastic. I removed the power cord if the LED light stayed on. I didn't know this would gave me hell moments later when I reconnected the power cord and turned it on. The PC fan was howling at top speed. I thought my lousy Dell had reincarnated itself into this Acer. I quickly powered it down. When I powered it up again, the bios date settings was messed up. Google and Adobe security certificates became invalid and in a hurry I missed changing the year and for the next few hours wondering what was wrong. The problem finally went away when I flipped the year from 2009 to 2011.

I think this PC is living its last days. Might need another visit from the tech guy. The three year warranty will expire in early May this year.