Why is my model broken after I install 9.0 Service Pack 2?

Answer

Note:
This article pertains to ArcGIS versions 9.x. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.

If the model contains any of the following tools, such as CreateRasterCatalog, CreateRasterDataset, MosaicToNewRaster, or HotSpotsRendered, the model may have been broken because those tool signatures changed at ArcGIS 9.0 Service Pack 2.
The signature changes are as follows:

• CreateRasterCatalog - The spatial reference parameter was changed from optional to required.
• CreateRasterDataset - The spatial reference parameter was changed from optional to required.
• MosaicToNewRaster - The order of the following parameters was changed: cellsize, pixel, pixel type, coordinate system for the raster.
• HotSpotsRendered - A distance band or threashold distance parameter was added.

Special care is needed with the four tools listed above. Their variables may have become disconnected and their parameter values may be have been cleared.
For more details on why models break and the methodology to repair them, see the Related Information section below.