New version 0.7.0 QT version for Mac has been released. Click here to download.This is a mandatory update, effective immediately. The older version of the wallets will not work after block 250,000, which will be reached sometime tomorrow, December 3.
See this page for a list of all wallet downloads for various operating systems:
http://www.grantcoin.org/use-grantcoin/wallets/ I installed the latest version of the wallet. Synchronization unit reached 250,000 and is already in place for 2 hours. What is the problem?