Hi Dan,
I am sure it was definitely 9.9 because I never released installer make by previous version. I will watch company network if this happen again. Just now I'm thinking about one possibility, I experienced strange behaviour in earlier setups made by AI with Install/Uninstall order. My early setups had same Upgrade code as setups created by Install Shield. I changed Upgrade code when I realized that. If this is case then this should not happen in future.