Desktop / Explorer icon instability & sudden shutdowns

I have an Acer Laptop running Windows 7 Home Premium 64 bit, on two external Acer monitors, MS Comfort Keyboard, and over the last couple of weeks, it has begun to show some real odd problems:

- in Windows explorer on one monitor, the contents display (Right side) will flicker between "Details", and random other displays (eg "List" or "Small Icons").
- Windows desktop icons will occasionally flicker between 2 different sizes. (Seemed to be related to mouse movement, but that might be a red herring!)
- a number of unrequested shutdowns have taken place, preceded (VERY briefly) by what looks like a "Permission Denied" message box.
- when working and producing data files, occasional "Permission Denied" messages appear, but these can be overcome with a "Re-Try". Irritating but not earth-shattering.

I have set my only user ID to have full access in a bid to address the "Permission Denied" errors, and this did seem to result in a reduction...

Have been running the machine for a few years quite trouble-free, and I am at a complete loss as to why this might start all of a sudden.

The only major change I have made recently was to install a WD MyCloud external drive on my hub. Their software was installed, but when "Permission Denied" messages started appearing when working, all the software was removed.

I have scanned the machine with Norton 360 - nothing disreputable found.

Can anyone offer any guidance on what I might try next to resolve these glitches?

Thanks in advance...

Thanks ThrashZone,

Yes, problem with Explorer happens on only one monitor (HDMI) but not other (VGA), but if you drag the window across screens, the fun gets much more interesting... behaviour of icons can be provoked into swapping, if you see what I mean.

The desktop problem happens on the Primary (VGA) connected monitor. Haven't swapped to using HDMI as primary, but there's a weekend coming up to experiment...!

Everything has now quietened down for the last couple of hours - ever since I placed my original post, bizarrely - but will be sure to follow up on the malware links.

Cheers....