Maybe I am not clear enough?
Zam, you need to post the EXACT values that worked for each account. You already posted that changing them was successful, but then when you set them back to what they were before, the icon disappeared again.
So, please complete the following tables.
Admin account, settings working correctly (tray icon shown):
screen refresh frequency:
screen resolution:
colors:
fonts DPI:
Admin account, settings not working correctly (tray icon not shown):
screen refresh frequency:
screen resolution:
colors:
fonts DPI:
simple user account, settings working correctly (tray icon shown):
screen refresh frequency:
screen resolution:
colors:
fonts DPI:
simple user account, settings not working correctly (tray icon not shown):
screen refresh frequency:
screen resolution:
colors:
fonts DPI:
In addition, please indeed run the removal utility for previous security tools, before testing the combination of settings that work or doesn't work.