When the pc (HP Compaq desktop, 2 yrs old - the problem is recent!) is booted up, it goes through the normal processes whach are well known and too long and tedious to list at the moment, but the wallpaper appears and then the shortcut icons on the desktop start appearing but there are one or two icons (not usually the same icons) that don't fully load (the basic shortcut is there but without the picture [just for example and not necessarily the icons affected - a blue Z for zonealarm, the fox on a globe for firefox etc, instead you just get the basic windows generated shortcut icon]) The task bar in the bottom right doesn't have anything (other than the clock I think - will check next time it happens). It will sit like this for ...? well several minutes/indefinitely, I usually get bored and try the only known cure (to me) which I will describe in a moment. The screen stays as described above, the cursor appears ok and is moveable but it doesn't operate if clicked on an icon, and if hovered over the START button - bottom left - it instantly reverts to the 'hour-glass' busy shape.
My only known cure - press ctrl/alt/del then in the task manager select ShutDown from the drop down menu (the cursor works ok here), then Log off Administrator - after a few seconds a box appears - explorer.exe (why can't I remember the wording - I've seen it often enough!!) needs to be shut down because it isn't working, click shut down and the screen goes to the blue 'administrator' screen. Click on my name and everything loads tickety boo!
I have carried out a CCleaner scan, MalawareBytes scan, Spybot, and AVG antivirus scan but as the problem is somewhat erratic I can't say that any of these did any good (no obvious threats found but plenty of 'junk' was cleaned). I have just -today- removed and replaced AVG antivirus as it was freezing the pc whenever it updated but even after it's full removal and purging of the post AVG system, when it rebooted - same problem as above. Will supply any further info as requested but the e-mail was long enough already :-)