C3s don't go bankrupt, not any more, the game masters have build in many precautions to such things, to prevent game abuses. Quiet some time ago, many players paid for their entire game, based on C3s taking in extraordinary loans. the game master wrote in a safety net for C3s, to prevent players from robbing C3s, via offering loans. although, with out looking at it, i'm not 100%, but you can look at that, go to the country's main page, and click on "Employment Index" and notice how many workers are needed for 100% production, you'll probably notice at least one category, (probably most,) that just doesn't have the available workers.
that said, i'd imagine that what your actually noticing, is that the corp was build right before, or right after the country was de-registered by a player. resetting the pop to a base level, but leaving all the old corps in it. that often results in 2 many corps in a country, and raising salaries to soak up enough workers is difficult.
what you should do, is use the option to move the corp to another country, that has the available workers.
additionally, in cases like i described, by being patient, you can pick up some cheap corps via bidding, or via shares, after the corps market value have had time to adjust to the lack of a real work force.