Another strange thing happened to Orlando Centawski when he was swimming, he stood on the water and played his handheld - very biblical!
I have two Neighborhood lots next to each other where that happens frequently. The only peculiar thing about them is that the pool is one tile away from the edge of the lot on both. Not only do Sims walk and talk on water on both lots, but I can see the pool next door through the wall of the lot I'm playing on. Having pools that close together was never a problem before Nightlife, so I chalked it up to neighboring lots being somewhat more "active" now ~ clickable, visible, etc. Oh...I also cannot remove or alter either pool.
![Undecided](/smf/Smileys/default/undecided.gif)
I also have one Community lot where Sims occasionally stand on the pool water and talk; the pool there is also one tile away from the edge of the lot, but the lot next to it is unoccupied. So I think that's the common factor, at least in my game: Pool walls too close to the edge, so the game gets confused whether it's a pool wall, or a regular wall, or something.
Any of that sound familiar to your situation?
I'll check it out - so far he's the only one on the lot who has done this but I hadn't thought to think it could be where the pool was positioned - good advice, thanks!