Task Bar Tabs Minimize / Close Fails To Respond

I have the oddest problem thats occuured in the past few days.It appears to be connected with the opening and closing and switching between tasks.For no apparent reason, the window you either want to close or one that's been opened and you need to say click on a button to start a task, just fails to respond. The only way to unfreeze and carry on with your work is to open task manager then you can click on any line of info on the list, dont take any action in task manager, just close it down. Then you can carry on with what you were doing.I'm running a relatively new machine with XP SP3.I've reinstalled XP and I've checked the machine for all sorts of nasties and there's nothing.

This problem can be in programs, browsers (firefox is the worst. If you load a new page, all the URL links will not be accessible, meaning when you mouse over they do not change the cursor, til you do what I mentioned withthe task manager).I have checked the system performance with task manager open and I am not getting any sudden drains on the machine, which is a pretty fast processor (dual core) and working with 4 Gb or RAM.One other thing I noticed. Say you have a page of icons on screen for example in control panel. Single click to highlight one of them and then I would usually double click to perform the action. Now I can't double click because I get a small box open withthe options available open etc.

I have no idea why this is happening, but I reckon it is connected to the problem.I am going nuts with this, because it is adding a lot of time to my PC day constantly having to unfreeze.If anyone can throw some possible causes. I honestly thought the reinstall would fix this once and for all but no such luck.If there's anything I have left out to aptly describe this problem, please ask.