Read the pinned threads, that's what they are for.
The Snowflake error is old and common. http://www.gamesas.com/index.php?/topic/781497-vistawindows-7-problems/page__view__findpost__p__11345653.
But before you go and do all that work, just http://www.gamesas.com/index.php?/topic/781497-vistawindows-7-problems/page__view__findpost__p__11352753. That will fix this problem, and many others that can occur.
Also... if you have both expansions, make sure to to install in this order: Morrowind->Tribunal->Bloodmoon
Install them when you install the game, because they update and fix many things in the original game. Not installing them will also limit your ability to use the essential community patches. (both depend on the expansions)