Strange problem affecting Mouse and Keyboard functions

Hi all, I hope you can help me with a very annoying problem that started around 6 weeks ago - that seems to be getting worse!

My PC is only around 6 months old - Windows 7, 64 bit, and has developed a very weird problem. It first started with my cut/paste shortcuts (Ctrl/C Ctrl/V) not working in Firefox - basically I can't copy anything when using Firefox (but then occasionally it DOES work). This works fine in Internet Explorer, however. Also in Firefox, when jumping between fields when completing a form, the TAB key no longer works (but again, works ok in IE).

The next, most annoying problem is the Mouse - a single click will often behave as a double-click. This happens with everything - when opening programs, email, folders, etc. Today the problem has spread to my Wacom Graphics tablet - the pen is now acting strangely as though it's also double-clicking a lot of the time, making work almost impossible.

I'm pretty sure this is a Windows problem, not my keyboard, tablet and mouse all going wrong at the same time. I tried a System Restore a few times when this first started, but the problems were back within a day or two. I've played with the mouse settings and tried changing the speed etc, but this hasn't worked.

The problem doesn't happen every time - I would say about 60% of the time it doesn't work properly.

Does anybody have any advice as to what I can try, to find and fix this problem?

Many thanks in advance!

Sharon

Thanks very much for the replies!

Well I'm pleased to report that the keyboard problem is sorted - it was a Firefox add-on problem. Putting Firefox in safe mode stopped all the problems, and after some testing it turned out to be an extension (SEO Blogger 1.0.8) which I've now disabled, and the problems have all stopped.

It must have been coincidence that I had the mouse problem at the same time as the keyboard trouble. Also, I changed a setting for my Wacom tablet and that cured that particular problem. Bizarre that all these little things happened at once.

After some testing just now, the mouse did the double-click problem only once, so it's still there, but seemed a bit better? To answer your questions, the mouse is wired, and is fairly old. I'll find another mouse and test with that, to see if I get the same problems. It could be as simple as buying a new mouse (I hope!)

Many thanks for all your help! I did the Disk Check, with no problems - sfc/scannow found no errors, and a Malwarebytes scan came back clean.