**EMERGENCY** Filed Calculator is calculating all records, not my selection...????

Discussion created by adcimapguy on Oct 25, 2013
I am joining a table to my master dataset, making a selection of values that are not null (for some weird reason my select IS NULL isn't working, so I have to select IS NOT NULL then switch selection...????) then calculating a field. The field calculator is actually calculating all records, not just my selection. Yesterday it did this twice and I thought I was losing my mind because I wasted two hours of work by the field getting wiped with null values somehow, but now I see it happening right in front of my eyes!?

Does anyone know what is happening!? I know the software does some wild stuff and people think they are crazy, but this happening three times (restarted arc, my machine, and did it the next day...) makes me know I am not crazy, the software has something wrong with it...