This have todo with staking overflow mostly!

When you have more then 90.000.000 coins in one part and the next stake comes in, it can go over 99 Million and wallet is crashing.
it is very simple: Divide ALL your stakes by make smaller 50.000.000 parts and stake many. when you reached 85.000.000 in some parts, just divide again to 50 Million.
As long as every part is under 90.000.000 Coins you usualy become no problems.

Another way to finaly clean up this messes is to create a clean new empty wallet, and transfer all your variable coins in 50.000.000 parts to the new wallet and then delete the
old wallet. This way i stake without any problems since many months ;-)

Same when you transfer coins to exchange wallets: NO more then 99.000.000 coin in each send!
When one single part is bigger then > 99.999.999 you have a problem and can´t send from this part this way. For getting coins out
from a part which is bigger, there needs other tricks, like "half-syncing" the blockchain and stop at a point where not all inputs on this part in the wallet.
So you can send a part from this coins out, before it goes over 99.999.999 which ocurs, when blockchain is completly sync.

Crappy ways, boring, i know, but it works so far so save your actual coins until a real fixed wallet comes out.