I only have a few more suggestions.
1) Try installing nv112 now available.
Also, this build comes with 180.44 driver, you'll have to add the 180.50 manually. Also, please note the workarounds on this page.
2) Try the workaround I gave you earlier now that you've progressed with the 180.50 driver.
3) If all else fails, try posting to xwin_discuss forum for Opensolaris/SXCE
Sun graphics engineers monitor this forum and quite often respond to end user problems.