Make sure the TEMP folder exists on the drive selected to set the variable to and that there is 4GB of available space on that drive.
Output Image Quality For ArcGIS 9.x and above, in ArcMap, select File > Print, and ensure that the Output Image Quality is set no higher than normal. For ArcGIS 8.x, in ArcMap, select File > Page Setup, and ensure that the Output Image Quality is set no higher than Normal. For particularly large maps with a lot of raster data, the Output Image Quality may need to be set to Fast. See the link in the Related Information section below for more information about Output Image Quality.
TIFF Resolution Though the TIFF export format supports higher resolutions, setting large dpi values causes the TIFF export file to grow exponentially.
JPEG Resolution - Only applies to ArcGIS 8.x In the export options for JPEG, do not set the resolution higher than 150 dpi, as the JPEG export format does not support anything higher.
Spaces In Names If the directory in which the file is saved or the file name itself has spaces, rename the file or move it to a location with no spaces in the path.