Install Ub 8.04 LTS Dsktp on Tosh Satellite 1805-S273 seems to only partially complete, then hang

Pentium III w/384Mb SDRAM currently dual booted with XP SP3 and all patches; AOK.  No errors. Installed Ub with powerr-on boot to UB distro CD, seemed to partially install, then halt w/black screen.Subsequently tried to install from within XP; same result. both seem incomplete.  Puzzling.Ub distro CD checked with diagnostic routine; checks good.  Ran partial memory diagnostic from UB distro CD and completed first 4 testw w/o incident.  Will return and run them to completion, but suspect it may not be a SDRAM failure root cause.  Suggestions appreciated.-aj-