So I fixed it..
Prior to the 1.7.6 official release I have been testing different modules to handle google merchant center reviews and print rich snippet for effective product page crawling.
Apparently I installed a prerelease version of the productreview module. I believe I uninstalled the pre-release as it didnt show up under installed modules after the uninstall. it was gone. however it didnt remove the db tables.
After trying to figure out why the latest version wouldn't install i ended up checking the db, and i found remnant tables matching ps_product_comment_* from the previous install.
After backup I dropped the suspect tables, reinstalled the mod, zero error.