make sure that your wallet is properly synced, currently @ block 12225
I think that might currently be a problem for many

Mine repeatedly gets stuck at 10202, with the debug.log citing "ERROR: ConnectInputs() : tried to spend coinbase/coinstake at depth 408". I've got it wiping everything restarting periodically, but might as well wait for an updated wallet with a proper fix

I had the same issue, & this is how i fixed my wallet.
1. Close Wallet
2. Delete everything in %appdata%/slimcoin
EXCEPT WALLET.DAT & SLIMCOIN.CONF3. Edit Slimcoin.conf, delete EVERYTHING and paste this :
server=1
daemon=1
rpcuser=USER
rpcpassword=PASSWD
rpcallowip=127.0.0.1
rpcallowip=192.168.1.*
rpcallowip=localhost
connect=144.76.139.111:10000
4. Be patient & let it sync COMPLETELY
5. After its done, go back to %appdata%/Slimcoin
6. Edit slimcoin.conf, delete EVERYTHING & add this :
I will be taking down node 144.76.139.111 in 10 minutes. Use a different node for syncing.