I get the out of memory crash on occasion. It never really bothered me much because it still saves the current state of the simulator.
The thing that really steams me up is the ootp vanishing act. I had to switch to auto-save after every single day because I've lost too much when I had auto-save at once a week. Just a few days ago, I lost hours worth of work and 4 days of games due to the vanishing act. I wanted to put my fist through my screen or just cry. Maybe both.
Before anyone suggests...their is nothing out of date, like drivers, or anything goofy with windows. In fact, I did a fresh install of Windows about 3-4 weeks ago. It vanished before I did the reformat/reinstall and it vanishes since.
There may be some other little things that I can't think of now, but overall, I have loved OOTP 21!!!