I didn't know that Norton AntiVirus had a goback facility. On the assumption that he's used a goback facility then the question is why - did he have a serious problem before?
As a first step I would let the thing boot into Safe Mode and then have a look at Device Manager (Right click My Computer>properties). If all looks reasonable here then try Start>Run>SFC to check that system files are undamaged and exist - have your original W98 disk ready to restore any missing or corrupted files. Try a restart.
If this doesn't work then boot up whilst holding down the F8 key. Choose step by step start up (you confirm each action) and watch to see what part of the startup throws the wobbly that causes the default into safe mode.