saveing sessions

[AB80135]

anyone shed a bit of light on this problem for me,after driving a session for about 3 hours I saved session when I restarted the session none of the signals worked some signals were faceing the wrong direction and none of the trains obeyed any of the signals that were the right way round neither did they stop at stations or any of the industries nor did they follow thier schedules,it had become a total free for all:'(.Thanks in advance for any help

 

[oknotsen]

Start with posting a bunch of more details:
What version of the game? What build?
Which route? Any specific session?
Any other problems at hand?

Signals usually don't just magically face a different direction, so I am curious here.