Is the switch just too closely gapped and being triggered by the vibration of the flipper coil? Put something in between the rollover switch contacts to prevent it from closing and play a game. Does the problem go away? If so, it is a gapping issue.

Can you find the switches on the switch matrix and let me know which ones?

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Ok, so you can see from this image, that the lane switch is the same as on the switch diagram above as the one labeled "right flipper button". That is in the same return row as the "top left lane switch". I'm guessing that when this happens, both the 1st and 4th balls are in the trough. So, I'm guessing a shorted diode on one of those 4 switches. I would check the 1st ball trough switch first for the shorted diode.

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Great! I’m glad that solved it. I’ve learned everything I know from diagnosing diode problems from this excellent video by terryb

In your case, current was going up column ST0 when that column was pulsed, over through row I0, through the closed switch in trough 1, through the shorted diode, which then allowed current to go down column ST2. Because the flipper switch was closed, the current was allowed to go out row I4. When the computer saw a signal at I4 when ST0 was pulsed, it read it as the lane switch being closed.

The video explains it a lot better, and with pictures!