I'm using Arc10 to try to buffer some polyons (in a shapefile) that I have merged together from separate polygon shapefiles generated in an earlier version of the software. The polys are in GCS (NAD 83), as are the points & lines that I have been working (which have all buffered easily). No matter how I try to buffer the polygons, I get "unknown errors" and "geometry errors" that seem to relate to the XY environment & extent?? I've tried importing the shapefile into a geodatabase & setting the "advanced geodatabase" environment settings in the toolbox before running the buffer command, but I still get the same errors. I've tried projecting the polys into Alber Equal Areas before running the buffer command, but with no more success. Any ideas?