what is your computer config, resolution, etc. While I have not seen the severity you have mentioned, those details will be needed to possibly resolve.
Easy problem is having to quick-save the first time you run, because there is a resident quick-save file from a previous version in the 344 download. Doing this avoids an inadvertant crash.
Don't reuse mec variant names you have already used in a given campaign. Known bug that is most likely fixed in the new release (pending).
have NEVER seen a crash in the pilot sreen, either in 276 or 304.
Advice, get a fresh download of the game before re-install, or revert to 276 until the next release.
Note: 276 has a bad habit of loosing money if you buy resources and then toggle back and forth between screens. THis problem does NOT occur in 304.