A -192 error is a "resource not found" error. Usually it is a sign of a corrupted program; reinstalling the affected software usually fixes the problem.
However, I have now gotten reports from several readers (Ryan Krueger, Owen Hartnett and Robert Denton) that claim a sudden increase in the -192 errors after updating to Mac OS 7.6.1, especially in the Finder. Apparently, the error box appears with an OK button; but clicking the OK button just leads to the re-appearance of the message. This happens most often for Owen when he tries to open the root directory window of his hard drive. In what may be a related situation, Robert gets it most often when working with any folder than contains many (1000 ) files.
You at least need to restart to clear things up. In some cases, you may even have to reformat your disk.
Update: John Schwabe found that Now Utilities' Now Tabs was the cause of this problem on his Mac. This is not likely to be the cause for all users now reporting this problem.