CrystalViewer no longer displaying in webpage

i turn to the experts...i have a vb.net app that displays crystal reports via the crystal report viewer. no issues for the last 4 years! in development all of a sudden i try to display the same old static report...no report, not even the viewer is displayed. i've looked at the generated html code but very hard to determine the issue there. i can see the javascript for the crystalviewer. i can even create a test app and show the report with no problems, but my current .net solution has somehow broke. i've made no coding changes either...just a couple of display statements. i'm confused...any ideas or suggestions, please. thank you in advance!