Twice now a window has appeared :

"Driver Software Installation

Unknown Device installed

The software for this device has been successfully installed.

Unidentified Device            Searching Preconfigured driver folders... "

I'm at a loss to understand what this means - no new device has been added and I don't know where to look to track it down.  Advice and suggestions appreciated.
1) Look in device manager - any errors?
2) Do a complete system scan with BOTH your anti virus software AND MalwareBytes
3) At what point do you see that message?Allan - thanks for reply.

I did look in Device Manager when I first saw the message, and again this morning - I could see nothing to suggest an error, but I really didn't know what I was looking for.

I'll scan again with Avira antivirus and MalwareBytes to see if I can SPOT just when in the process the message appears (I presume that is what you mean).

I did both scans yesterday as part of another query that I had, and POSTED logs for them - if it's any use to you they can be seen in my post under Viruses and Spyware "Email problem/query" Feb 23.  They both showed all clear.Didn't mean to confuse you - the scans will have nothing to do with when the message appears, I just want to RULE out MALWARE as a POSSIBLE cause. I would, however, be interested in knowing when the messages appear (separate and apart from the malware scans) ie, when the system first boots to the OS, when you try to run a specific program, when you connect a usb device, just randomly, etc. Thanks.
OK, will do.