Did you select that model you want? Normally what I do is delete all the stuff around the model or object I want and then proceeded to fix it up. Once I have the model isolated I reset the xform and align the move tool to the center pivot. Then convert to editable poly and target weld all the vertices to one. But that's with 3DS Max. Have you thought about switching? Also for half-life 1 beta have you tried running it in capability mode for Windows 98 or XP?