I have Sonar Platinum and have just updated Command Centre which advised there was an update
“SONAR 2016 Manchester Update 1”.
However when I ran the update it was stopped by Windows Security Essentials as it had detected a Trojan in temporary directory used for the download of the update. The trojan is named
“Win32/Varpes.J!plock”
Anybody have any idea what is going on here and what needs to be done?

Never seen anything like that.
 
I'd do a full system scan & clean up and start the download again.
 
Run CCleaner to get rid of all your rubbish before doing a scan

Bristol_Jonesey
Never seen anything like that.
 
I'd do a full system scan & clean up and start the download again.
 
Run CCleaner to get rid of all your rubbish before doing a scan

I am pretty sure if the latest Sonar update contained a virus, this forum would be lit up like a Christmas tree. 

I would also do a full scan with Malwarebytes Antimalware.  http://www.malwarebytes.org Remember when you install this, do a custom install and keep an eye on the box that says activate trial.  This is a free version of the tool, but some people leave that box selected and end up installing the 14 day trial of the pro version and then getting nag screens to buy the pro version.

Yes, I use Malawarebytes on all my computers, including those at work.
 
You should use this in conjunction with a good AV

Microsoft Security Essentials is probably installed on thousands of Sonar user's computers, so if this were a legitimate alert related to infection of the CCS or Sonar it would have alerted on many many users. If it were a false positive (as is often the case) it would still have affected the same number. The fact that it is located in a temporary folder used by the CCS is possibly coincidental. This is probably a unique event on your system and most probably does represent detected malware, although not received from Cakewalk. Good luck. 

I did a little research. Apparently this is an extremely pernicious virus and can enter your system through any one of a number of ways. Do a search and you'll find several hits about removal.

Thanks to all for the advice. I will now work on the problem.

Ran a system clean up then deleted the original Sonar update download. Ran Command Centre again and this time download and updated completed without a problem.
Thanks to all who responded, everything is now ok.

Excellent news!!