The clue was in a reply to the thread “126.96.36.199 does not close on my xp” about ImgBurn being blocked by Trend Micro Internet Security.
I use Trend Micro Internet Security 2013, and adding ImbBurm.exe to the TIS exception list resolved the problem. In fact ImgBurn 188.8.131.52 now closes faster than 184.108.40.206 did, it now effectively closes instantaneously, whereas before it also took a few seconds. I think this is due to having a local exception rather than a Cloud based one.
For Users of TIS add ImgBurn to the TIS Exception List as follows:
Open TIS Main Console Click on the gear wheel icon and go to Exception Lists > Programs/folders Click on +Add, browse to C:\Program Files (x86)\ImgBurn\ImgBurn.exe and Open - ImgBurn.exe should appear in the Exception List Click Apply, OK and close TIS Main Console Test
NB! For 32-bit OS’s ImgBurn will be at C:\Program Files\ImgBurn\ImgBurn.exe
Thanks for your help. It would be a good idea to put a note about TIS blocking in the program Readme