The problem is most commonly associated with another application on your computer hogging all of its resources, so that your browser can't function properly.
So you need to try to find out which program is causing the problem (although my money would definitely be on your antivirus program):
When you first turn your laptop on, open the Task Manager (via right-clicking on the Taskbar at the foot of your screen). Click on the 'Processes' tab' and then on 'Show processes from all users'. (If you're asked for permission to continue, grant it). Maximise the window (by clicking on the square at the top right) and then minimise it down to the Tasbar (by clicking on the line at the top right).
NB: It's important to get the Task Manager running before the problem appears; you won't be able to do it quickly when it does.
Then, when you get a 'not responding' message (or similar problem), click at the foot of your screen to maximise the Task Manager again. Look down the CPU column for anything that's particularly high. Only 'System Idle Process' should be in double figures; if anything else is then you might well have identified the rogue program.
Then look down the 'Mem Usage' (or 'Working Set Memory') column for anything that's got a really high figure. Again, that could indicate what's causing the problem. (Only your browser should have a figure greater than 100K)
However, if (as I suspect will happen) you find that it's 'svchost.exe' that's got a massive figure there, you'll need to find out what's making a call upon it. (svchost.exe is the program that Windows uses to download files; you need to know what has asked it to do the downloading).
So you need to look very carefully at the figures in the 'Mem Usage' (or 'Working Set Memory') column to find one that keeps changing every second or two. (The figure itself might be quite small but it's the constant changes that indicate that it's making a call upon svchost.exe).
My guess is that you'll find the program you've identified is the one that updates your security program. (For example, if you're using Microsoft Security Essential, you'll see the figure for MsMpEng.exe constantly changing. If you're using Avast it will be AvastSvc.exe that displays the same behaviour).
Once you've identified the rogue program you'll then have to work out what to do about it. If it does turn out to be your antivirus program you could either try uninstalling it, and then reinstalling it, or switching to a different anti-virus program.
For example, I've solved 'not responding' issues on several computers that were running Microsoft Security Essentials by simply ditching it and switching to Avast.
Good luck!