I'm Puzzled and Bugged: An odd mouse click problem on Win7

Updated 12th October: Problem has vanished! Read below.
I’ve come across a very annoying and strange defect on my Windows 7 laptop. It really bugs me!
Here are the patterns I’m seeing:

• Sometimes, the minimize/restore/close buttons don’t light up when I hover the mouse above them. Clicking them has no effect. Whenever this happens, Alt-Tab’ing to another window and than Alt-Tab’ing back again restores them and they work again.
• In Firefox, this happens as soon as I have clicked once somewhere inside the window.
• The same applies to Thunderbird, my e-mail application.
• Mouse clicks in popup windows sometimes end up in the window below the pop up window. E.g. clicking the close button on a popup window does not close the window, but does something in the window below it.
• Other applications don’t seem to suffer from the problem, but has other types of odd mouse behaviour.
• In Libre Office, I can’t click-and-drag to select text any more. Text selection is only possible by keyboard.
• The scroll wheel doesn’t work in Internet Explorer
• Capture One Pro 6 (a photo editing application), dragging sliders (to control photo appearance) no longer works.

I’m puzzled and bugged. But I’ll find out what’s wrong.
Oh and, by the way: I have tried restarting. It doesn’t help.
— Update 23rd September:
As per Michael Boltons suggestion, I connected a new mouse: A Wacom tablet. It didn’t change anything.
I ran Windows update and Sony’s own update tool to update various drivers. It also didn’t change anything.
I’m pretty sure the problem started in the middle of the week. At first, I just thought it needed a restart and I was too lazy to do so, so it might have been there for a few days before I reacted. I haven’t installed any software, but I have run Windows update. The update log shows this:

I’ll try to uninstall the Silverlight update, as I’m suspecting it as ‘new and fancy technology’ might put in hooks in odd places in Windows.
— Update 12th October
I have a confession: The problem went and came back a few times, and now it’s gone completely. I feel like a lousy tester since I haven’t been able to dig out what caused it. Uninstalling software didn’t help, updating drivers didn’t help either, and even updating various software from Firefox, Thunderbird and Capture One Pro did not change mouse behaviour. I’m let with a well working laptop (that’s good!), the memory of a very annoying problem, and some lousy theories about what caused the problem.
Is this a case of a system error, which cannot be understood in the sense that there was a single cause, but has to be analyzed using a system perspective: A system of thousands of components interacting in complex ways? Like I suggest we analyse Black Swans in IT systems?
In that case, did something turn up the heat? I was a bit stressed myself at the time, but no – I don’t think my mental state affected this. And I can’t think of something.
My best guess is that a Firefox plugin for html debugging in combination with a specific version of the application and possibly some driver issues somehow ‘turned up the heat’ causing the problem to materialize. But it’s only a guess.
(By the way: I could have done like most would probably do: Reinstalled the pc or bought a new one. But just a few weeks before I did actually reinstall it completely with a new SSD and more RAM.)