So actual bug in mulitplayer. I've kept save games from before and during, and after the bug and can send them to you. Basically, occurred to Alkari player in this game after he had completed researching Adamantium Armor. Was given the upgrade ship option? Even though he didn't have sufficient money he was able to select the button to upgrade his ships. His total wealth went to -1400 BC (had about 1200 before so it was about 2600 BC to upgrade) and then it instascrapped a bunch of his ships at the end of his turn.

Read at least one other report of same thing, also a multiplayer game, so might be an MP only upgrade bug.

No additional bug report on that, just a suggestion to ship upgrade. It would be nice if it was possible to upgrade ships via the production of a colony instead of purchasing it.

--> Move ship to a colony.
--> Choose to upgrade.
--> Decide whether to buy with money instantly or to let it be refit via the colony, taking time and setting back the other production orders.