Hello Graham!

If you are not able to update your software and you receive the 406 error message, please do the following:
- disable antivirus and firewall because they could block the program's connection to the server.
- make sure you aren't using Proxy
Now try again. 

If you receive the error message again, please restart your pc and close the programs that eventually open when it starts. 
Go into the program file and start the "imUpdate.exe" in order to force the update.

I wish to remind you that if you have Windows Vista / 7 / 8 you should do this after starting your program as administrator: right click on the program's icon then select ''run as admin''.

If you still have issues, please download the program from the ''download'' section here on answers and install. Here you will find the latest version of your program. By doing this, you can delete your old version and install your new with it's latest update.

I hope this helps,
Samantha