Best posts made by p-h-f

@burnout426 Thank you for your quick replies. I had totally forgotten about the command line switches. Not used since Opera 15 or before. Sandbox is disabled by default on his PC. I may try Opera Developer, but I have searched for similar reports and not found another, so think it is unique to his computer. I am not sure if the Cortana issues arose with other AV programs, it was not noticed until the re-install of AVG. I will try your suggestions and those of @yanta. Again thank you for your quick replies. I think I am in for the long haul to resolve this issue.

After a new clean install of Windows 10 2004, Opera consistently shut down after a few seconds. I thought that this was a problem with build 2004, This was partially correct.
I found that the problem was with the graphics drivers on this computer - AMD ATI Radeon HD 6410 which was installed at the same time as Windows. The clue was in the Events viewer|Windows Log|Application which showed consistent errors with ATIeRecord with event ID of 16388. Opera failed after these events.

AMD no longer support the Radeon 6000 series chipset drivers. The cure for me was to enter c:/AMD/Radion-Software-Adrenalin~~/Bin64 and select the "AMDCleanupUtility". This removes the ATI software and drivers with exception of the Chipset drivers. It returns the PC to using the basic video driver which works correctly and Opera is stable again.

I hope this may assist others who have reported this issue, in resolving the problem. From this position it may be possible to add additional video drivers incrementally if required, while monitoring the event viewer and any potential failures.

I run Opera (latest update vers.68) in Windows 10 Pro. with dual monitor (extended option). I have Opera pinned to the taskbar and usually an additional shortcut on the desktop.

I have had a re-occuring bug since Version 65. It re-occurs about every 3-6 months and shows in one of two ways. 1) when clicking on either icon the taskbar icon is underlined and shows a thumbnail but Opera will not open to full screen. 2) a second icon is generated on the taskbar but behaves as in 1) above. the second icon disappears when close window is selected.

I have found that I can correct this by unpinning the taskbar icon, then deleting the desktop shortcut. Go to the Opera launcher location - for me this is C:\Program Files\Opera\launcher.exe (check- Help|about opera-Paths)
Right click on launcher.exe and pin to taskbar. If required, right click and create shortcut & drag this to the desktop.

I cannot duplicate the problem after curing it to attempt to find out why this happens, so I hope the above may help.