I keep my undo's at 50 (default). I also downloaded a free "ram watcher" program. It helps but doesn't always catch when the program's about to say, "Don't do one more thing, or I'm gonna shut down." I too, have a gig of Ram and as long as I'm careful and saving pretty often (every 3-5 minutes with a large open file, I don't have any problems. The other thing you can do if you notice Flexi starting to behave erratically is save and then shut the program down and restart the program (not the computer; not necessary). This takes all of what? 10 seconds? and it resets your ram.
For nxtreme, so many windows = ram being used. Prioritize what you have open and close what you don't NEED. With the gig of memory I have, I keep less than 5 or 6 open maximum at once.
Slapakiss, you're just running out of ram as well. Save often and restart the program from time to time.
It never fails, you're working on a sweet looking piece of art, you know? You're in that creative vein and the ideas are flowing, and then BOOM, the program says "Sorry, unrecoverable system error." And then you start kicking yourself for not saving. Having that happen a few times during your day can make you feel like you had a lowsy day.
Every now and then, it's going to happen; technology is not flawless, it's man-made. For a long time, I had a sticky note on my screen that said SAVE!!!. It's worked for me. Ctrl "S" has become as automatic as tying a shoe.