I think that checking door switches is a great idea.

An old time mechanic once told me that switches are a weak point with Volvo electrics.

I would pull one switch out and drive the car a couple of days to see if the problem is gone, I would not put any back until I eliminated all of them.

Check the first switch to see if it is open or closed when it is pushed in.

Why? If the closed door position has the switch in the closed position, the switches could be in series, and any one could break the circuit, causing a relay to activate things.

Of course, tape the connectors so that they do not short out

Any connectors that you take apart should be cleaned as much as possible and then treated with dielectric grease.

Almost everything electrical that you take apart on modern cars has been treated with dielectric grease.

Maybe start by checking the door switches, beginning with the driver door. They can be problematic. Carefully remove each one straight out as the contacts can easily spark and arc on the chassis. Make sure all wires are snugly connected, the switch is relatively clean and remove any rust on the chassis. A loose or chafed wire, worn fuse or loose relay would seemingly be the most likely candidates behind your intermittent problems.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now