That's strange. Turning on 3D mode only effects the rendering of the scene; it shouldn't make the scene disappear.
Does turning 3D mode off make the solar system come back?
What 3D mode are you using? There are 3 options under settings (from the main menu select "Settings")
Does the whole scene turn black when you turn 3D mode on? Is anything visible?
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Try this:
1 - Load a system
2 - Turn on 3D
3 - Send me feedback and mention that you're "xts44" and are having the "3D disappear" problem (feedback will send me your log files, which might help me figure out what's going on)