That error indicates a corrupt database, possibly the blockchain.
You can try going to " \users\<username>\appdata\roaming\Goldcoin (GLD)\"
and then deleting these files:
database - folder
blk0001.dat
blkindex.dat
do not delete any other files.
Then restart your GoldCoin client. It will have to resync the blockchain and may take a few hours.
Good Luck, let us know how it goes.