It seems now that if I select a race as my own, the techs and any other changes sometimes go away.
You've just got bitten by what i call the race files backup snoop.
Every time you alter a stock race (by fiddling with any settings during the setup phase), your C:\Docs.. folder receives an 'opponent like' but still valid individual race file (which is, for modders at least, an extremely precious reference to have handy for later manual edits).
The side effect is that when you go select the maxed 9 AI races to play against, any of these extras are replacing what default values are usually loaded through the main RC.xml.
Every time you start new games, these files are resilient unless simply deleted from C:\Docs.
