You've got a power and signal sequencing problem. Generally, both supply rails of a dual supply OPAMP should always have their voltage applied (and removed) at the same time. Also, no signals should be applied unless the operating voltages on the supply rails are present and stable.
For specific OPAMPs and application circuits it may be permissible to apply signals before power. e.g. if the absolute maximum input voltage range extends considerably beyond the rails, or if the input circuit has enough resistance to limit the input current enough to prevent damage. See OPAMP datasheet + any available manufacturer's application guides for that OPAMP, and consider carefully if the specified permissible input voltage range could be violated transiently during powerup or powerdown.
If you use mechanical or independent supply rail switching, or there is any other way one rail may become disconnected, even momentarily, it may be helpful to put reversed biassed diodes between both rails and ground so neither rail can be dragged past ground when it isn't powered. It will still misbehave, but usually less severely than if a rail is totally disconnected and floating.
I would also recommend 10K resistors in series with each input (i.e. one between Vref and in+ and the other in the feedback loop, so the input bias currents for both in+ and in+ cause similar voltage drops).