I also have a problem with my wallet.dat file. If I start JackpotCoin QT with an empty wallet it will sync 100% but if I then quit QT and restart with my wallet.dat file it crashed right after the "Loading block index" finishes. My wallet.dat file is about 72mb large and contain many thousands of transaction and I assume that is the reason it crashes. Is it some how possible to use the wallet with CLI instead?
Mine is 50MB crashes at the same time as yours. i have thousands of transactions also from staking. my second wallet i am not letting stake so it doesn't happen again but would really like to get my 10million JPC back.