Thank you Dias.
I searched and scanned many times without finding any trace of the files you mentioned or any other malware. I did a Repair install on my cloned backup (Slave) hard drive and the problem disappeared when booting from that drive. Decided to do some more investigating on the main (Master) drive and was advised to search for a file named Echo, with or without an extension, on my Path. MS Search, Dir and Explorer revealed no trace.
Finally I installed a search program named Locate, the two versions of which run in Windows or from the Command Prompt. Locate32 run in Windows revealed nothing. However Locate.exe run from the Command Prompt revealed a 0-byte file named Echo in the root of C: without a creation/accessed or modified date or times, and with the Attrib of only A(rchive). Del deleted this file and Echo. is now back to normal. As already stated Echo has always worked, only Echo. was a problem.
This resolved the problem but raises lots of queries for me:
1. What created the Echo file?
2. Why did a Repair install remove it, Repair is not supposed to remove or replace non-system files.
3. How can a file, even an empty file, be created without dates?
I know, or think I know, that you won't have answers but thank you for your interest.
W.