Rare vegebubbles appear randomly in the fields. To increase your chances of finding them, you need to improve the 'efficiency' stat (and I just realized that I completely forgot to explain this stat in the game >.<).
Note that you can also get them 100% of the time by using the right fertilizers (unlocked as you progress in the storyline with Tracy).
I just tested it, and it should work. If you're at the beginning of your relationship with Ninie, you should be able to 'unfreeze' her during the animated scene by breaking the ice with your boldness stat (it should be high enough to at least unlock the scene). If you're further along in your relationship and have already passed this point, the next scene triggers automatically when you enter the kitchen with Ninie (so I presume you're at the beginning).
I'll need more details...
what did you click on to generate the error? In which scene did it occur? Does the error appear in the middle of the scene or during a loading screen?