Can anyone please explain in layman's terms how to identify or resolve my computer that has an intermittent freeze where it completley stops, and seems to be checking itself, before springing into action again after a 20-30 second gap. it seems worse when you open additional windows within a site.
A PC is a complex mix of software and hardware, with data flying round the place at alarming speeds, and pieces of hardware interfacing with each other in micro seconds.
It could be hardware, it could be software.
It MAY be overheating, but does not sound like it.
If you are running Windows have a look in the Event Viewer to see if there are any Application or System messages that give any help.
When a computer runs out of real memory it copies some memory to hard disk. This can take a long time (in computer terms) and the computer can seem to freeze.
If it is REALLY low on real memory it can have LOADS of memory paged out to hard disk.
The trouble is that it then has to keep copying data from real memeory out to hard disk, then data from hard disk back to real memory.
This is called thrashing and a computer can spend so much time copying data back and forward it cant get any other work done.
This may also happen if you have very little room on your hard disk.
Check how much real memory you have (RAM) and also see if you have plenty of free space on your hard disk.
You may have to add more memory to your computer (or maybe stop having so many program open).
Also see if you can stop unimportant programs starting up when the computer starts up.
Before you open any applications, right click the task bar and select task manager. Select the performance tab and monitor the cpu / memory. If these are high at the very top, select the Processes tab. So, if the cpu is high, click once the CPU cell (that says CPU) once. This will give you the highest number and what application is using it. Do the same for memory. This will be a start but as the first answer says, it could be a numbr of things in the sw / hw