you might have a trustworthy soul open and clean the innards of your laptop after 4 or 5 years because there might be dust and dirt blocking the vents and fans which affect internal cooling.
50 degrees C isn't that hot and well below the max temp of 55 degrees C.
if cleaning the machine doesn't help, then your mainboard might be breaking down and the laptop is on its way out. I hope it is only the harddrive dying because that can be cheaply replaced. don't trust software to accurately report internal temps unless you know that the sw is reading actual temperature probes built into your machine. one possibility is a fan on the cpu heat sink is clogged with dirt. the speed of such a fan can be read by software if you have such a cooling fan.
have you ever run a SMART test on your hard drive to see if it is dying?
i think it is time to back up all your data and expect the worst.
opening the window should have no effect on the internal cooling of the machine unless it's the dead of winter.
good luck
-pi