The second one is only confusing because you're trying to find a cause and effect between 2 events that simply happened to happen at the same time. Though in practice the events may have an underlying common cause and so do show up more often than you'd expect.
A concrete scenario is a community bank in a place where a major employer just did a layoff. The value of the mortgages is now impaired because some people won't be able to pay them back. The laid off people also need most of the money in their checking accounts because they have no job. The bank now has a challenge - its cash reserves don't meet anticipated needs, and it can't sell the mortgages to get more cash.
The troubled bank has a good chance of surviving unless the third leg of the trifecta shows up - word gets out about the bank's trouble. Now everyone scared of losing their checking accounts all show up to withdraw money at the same time. The bank doesn't have the cash for this "run on the bank", and goes bankrupt.
This scenario was historically common. People accepted it until there was an event during the Great Depression where enough banks went under at the same time that people got scared about what were otherwise healthy banks. Even though their assets were good, they couldn't pay out all accounts at once, and began going under en masse. FDR took fairly drastic actions to fix this (bank holiday, confiscating gold, etc) and then put in the FDIC to stop it from ever happening again.
There is a well-known portrayal of this run on the banks in the movie, It's A Wonderful Life.