At midnight New Years eve the world could turn into a technological pumpkin. These conditions could bring on a national state of confusion thus precipitating the time when we cannot buy or sell. All these things could happen. WE don't know. Computer problems are not mentioned because they did not exist, at least not that we know of.
Some people think they did exist prior to the flood, but no remains have been dug up.
Let's look in Luke 21. Here's another sign of the last days. I believe that these two verses are not totally fulfilled yet. There will be signs in the sun, moon and stars. On the earth, nations will be in anguish and perplexity at the roaring and tossing of the sea.