yes indeed dust clogging up the pc is one of the top killers, heat kills.

If you did not clean the fans real good you need to do that too. make sure they are all working still because some may have burnt out.
Cleaning the computer and its components

Overheating because of dust buildup is a very common problem and you see cleaning instructions given out on here almost every week

If you keep the tower on the floor under the desk it will suck in 10 times more dust than if it was raised up just 6 inches.

owbist, you are so right. The only computer that has gone bad on me was sitting under my desk. I had it in a rack made for that purpose, but still died.

Pair of scissors, some box tape, and a cheap fuzzy furnas air filter can do wonders.

If you keep the computer in a computer stand with a door over the unit, keep the door open when in use.

Also as I have shared before, if you have a built-in and the back of the computer storage area is solid with cable holes take a cutter and remove the the solid material.

If you have a need to keep perhaps pets and children from accessing the rear of the unit a plastic (not metal) screening can be stapled in place which would make it easily removable for cleaning.

DA

My husband does woodworking as a hobby so he built me some nice little wooden pedestals to put my towers on that go under my desk that lifts them up about 6" off the floor, it has made a world of difference when I open them up to clean them now.
I have my new one up on top of the desk since it is so pretty with the see through case and all the pretty colored lights in side LOL. I do love the clear side panels I can see if it is dirty or clean quite easily and see all my fans are working too.

I think Mikie's idea of cutting out and installing filter material would be great

I would be afraid of the filtering stuff blocking air or even having fibers in it that would cause a problem. I used filter material for my pond pump, but washed it first and you would be surprised to see what washed out of it.

My husband does woodworking as a hobby so he built me some nice little wooden pedestals to put my towers on that go under my desk that lifts them up about 6" off the floor, it has made a world of difference when I open them up to clean them now.

I did the same thing but raised the stand to make sure the computer top was level with my desk ,this adding some more usable desk surface,plus a nice little storage space for wires and such under the tower.Also, I only need to clean it about once a year instead of once a month.

How to open the laptop- there are several screws on the bottom-there are some that are 'in a hole'- are these the ones that open the bottom? Does only the bottom come off- what about under the keyboard- how to get underneath it?

Laptops are different and the components are located in different places. I would not start removing screws from the bottom of the laptop since some control the keyboard, others are for the battery compartment, etc. So unless you have information from the manufacturer of your laptop as to which items are located where, you could cause damage.

Just used some "canned" air to blow around the keys and the air vents. Be careful because too much force can damage the delicate parts.

go to your manufacturers website and look up your laptop model and look for some detailed pictures of the laptop they usually have them with the compartments identified.

Besides RC's suggestion of going to the makers web site you might Google the model number. I found a site where there are pictorial tutorials for dismantling various laptops. BUT Grandms is right, you do not need to be getting inside unless you are willing to accept the fact you might mess things up trying.