VisBio writes all error messages to a file called "errors.log" in the VisBio directory. First, check that file to see whether the error output is present.
Alternately, you can take a screen capture. (On Windows, hitting "Print Screen" copies the current screen into the clipboard, which you could then paste into an image editing program such as Paint, then save it to a JPEG or other image file.)
Also, it is possible that VisBio is not locked up, but that there is a modal dialog box (such as the Colors dialog box) waiting to be closed before text can be copied from the error console.