Episodic failure of "X" to close page/screen

I use a Compaq CQ40 Notebook PC running Vista Home Basic SP2; 32Bit operating system; processor AMD Sempron; SI-42; 2,10 GHz.

Living in a quite remote area seeing a technician is not so easy. This machine has given me a little difficulty from time to time, but it has recently been quite stable.

Except that when I click on the ' X ' in the top R corner to close a window, sometimes it will not work, unless I click on it many times. Then the screen goes grey, and a message comes that saya that the programme is not working properly (as if I needed being informed of this). Then after several seconds it usually clears down okay, back to my desktop. Only rarely is any other ' X ' need to click on, giving me this trouble. Otherwise the machine works just fine. I use it not for graphics, pictures, games, or things like tweeter and such. Only eMail, word-processing with ord 200o only no office, and researching airline and aircraft and aimple things like that. Nothing arcane or esoteric.

I have twice now taken this to technicians who tell me that they cannot find anything wrong with it. (It is always the case - you have a strange noise in your car, but it will not be heard when you take it to the mechanic) Their being unable to find anything wrong has not stopped them from charging me for looking at it when I have left it with them for two days (one time).

Can anyone tell what I am doing wrong? Is this something that has happened to anyone else, or is it my personal problem only? I am not averse to paying service fees when a problem is fixed, but ... .

Help, please?
Kindest regards

LOL
Im currently having that car problem, so I know what you mean.

I would conduct the following test and/or changes to try to diagnose and cure.

Try in safe mode and see if it happens (report back)
Try in clean boot and see if it happens.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
Reset your browser. If it is IE, (Tools>internet options)advanced>reset). This removes the addons which will have to be replaced, but its very easy.
Try with anti virus and fire wall turned off. For test only. We dont want to spend extened time on the net without protection. If the problem is very sporadic, skip this for now.
Run a full updated anti virus scan
Download and run a full scan with malwarebytes.

Almost forgot. That x is just a short cut to closing the browser. Try the correct way file and exit.