HP Brio – reinstall problem

HP Brio running W98. Various problems (intermit BSOD, won’t shutdown, GPF’s etc) so I decided to reinstall W98. I ran setup from Win\opt\cabs and it completed OK but on restart it stops at the DOS prompt. If I type win it says I am MS_DOS mode doI want to return to Normal mode. If I enter yes the machine restarts, momentarily shows the Windows sky page and drops out to the DOS prompt again. It will boot in safe mode, but if I uncheck all boxes it tries to run setup (and fails) on restart.Anybody help please, I don’t really want to reformat.