I have the same problem. The wallet crashing during mining.
I solve this problem in the following steps:
1. Write to the coochie.conf nodes from the forum and active peer list
addnode=138.197.191.206
addnode=18.216.178.16
addnode=46.101.211.186
addnode=46.101.177.203
addnode=52.14.5.147
addnode=154.16.7.137
addnode=177.10.13.25
addnode=168.1.112.81
addnode=168.1.99.220
addnode=71.12.246.193
addnode=129.21.131.162
2. Open wallet. Wait for full synchronization and close it.
3. Make a backup copy of the folder %user%\appdata\roaming\coochie.
4. After that you can open the wallet and start mining.
If the wallet crash, just restore the folder from the backup. All you new transactions are downloaded from the blockchain.
Make a backup every two days. Then, during the recovery, loading from the blockchain will be quick and easy.
In general, it's good to have a fresh backup.
It's not very convenient but it works
ADD:
If the wallet crash while synchronizing, you can completely load it from the blockchain.
Leave in the folder %user%\appdata\roaming\coochie two files: wallet.dat and coochie.conf. Erase the other remaining files and folders inside. After that, start the wallet. It will loads everything again from the blockchain. This can take a long time.