Texture persistence problems

Hey, been using the new version of blender over the past few days after a few years of not using this software and i’ve run into some pretty serious issues with texturing inside blender. Twice already, in the middle of the blue my texture has been set to all black, deleting all progress, and numerous other times it has seemingly reverted to previous versions. Using alt s to save manually gives me a “cannot write to ’ ’ directory” error.

So first of all, whats causing my texture to randomly vanish? even if saving is working, it’s a bad thing if i can just randomly lose progress at any time unless im saving every brush stroke. Second, whats wrong with the save funciton?

Thanks for your expertise!