Md simulation

GROMACS version:
GROMACS modification: Yes/No
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I did a MD Simulation on spike protein for 50ns.
And I noticed that the protein (has 3 chains) keep flying apart after the simulation.
What can I do?

Could you describe in extreme detail what you did to set up the simulation, what commands you used for each step and copy-paste all the messages/notes/warnings/errors that were output onto the terminal during each step?