Thanks for letting us know!  This was a new product for us also, so we're figuring it out together!
We've noticed that two things will significantly help to reduce the case from tipping.  First, when loading, be sure to put your heaviest items all the way in the back, trying to avoid having heavy items in the front or in the front of any drawers.
Second, the orientation of the wheels plays a big role!  When the wheels are in a certain rotation, the case is more likely to tip.  The VERY easy solution:  roll the case about one foot backwards.  This will rotate the wheels so that they are in the optimal orientation to provide better support and help to prevent tips!
One additional tip from the factory... install the locking wheels in diagonal corners, then after rolling the bag as stated in the above paragraph, lock the wheels before using the Case.