FL300 glitch

Everytime I fly an IFR flight in one of my commercial jetsand I try to go over 30,000 feet, the plane starts to stall and crash at around 30,0000 feet. All my planes are stock planes from FSX.

Anyone know how to fix this?

What's your airspeed and how fast are you climbing to get to that altitude?

last time it happened, i think i was flying at 280-290kts at 1800 ft/min. Should i lower the feet/min to 1500 or 1000?

You bet you should, especially if you're flying a heavily laden aircraft. Try around 1000fpm and watch the speed carefully, it can shave off very quickly at this altitude. (PS: This isn't realistic procedure as VNAV/LNAV is used to control attitude based on holding a certain speed).

do you know anything about recoding flights too?

Unfortunately not a lot, but the best program to use would be "FSRecorder" I believe, and then using fraps to record your in game replay through FSRecorder. A nice little tip I've found also is to record in 1/2 time speed, and then speed it up to 2 x in your video editing software, that way you're getting double the frames. Although that's probably a bit too complicated for a beginner. Other than that I don't know much, sorry.