Sorry for the delay in coming back, just work and family commitments getting in the way!
When I got home the other day my wife had been trying a few things out (pressing keys in a random fashion!) and came up an ACMON Error message and something about a chameleon engine being out of service. I have downloaded the latest drivers just in case but Safe Mode wont open the zip file.
Where I'm at now. I've discovered that I can't run several things in Safe Mode such as defrag or open downloaded files. Check Disk came up clean and I've done a Disk Clean Up. I'll try the SFC this evening, I've just not had time these last couple of days to do much of anything. I have Malwarebytes already and this showed no sign of problems but Avast (free edition) shows three things in the vault (all dated from before the problems started) so I don't think they are the problem. CCleaner shows all to be well.
Sometimes it will load (mostly) in normal mode, except for no icons working, sometimes it will only load in Safe mode when all icon work but some things (like defrag) wont. Anything with an icon on my desk top works fine in Safe Mode except IE8 and Firefox. I'm afraid I don't know which edition of FF I have.
In Normal Mode My wallpaper, a photo slide show runs very quickly at first, every few seconds, then slows to about every 10 seconds which is where it's set for and then after a few minutes it all stops. Arrow pointer will move across the screen but turns to spining blue circle in task bar.
I'll be beavering away over the weekend as I have no work on and I'll report any progress as and when I can.
Thanks, as ever,