I am having a similar problem. Running 0.4.9 on OSX 10.8.5.
I upgraded my client to 0.4.9 a few minutes ago. When I opened it for the first time, it hung forever and I had to force quit. I did a restart and after launching for the second time it asked me if I wanted to reset the database, so I clicked yes. My account is still currently showing a zero balance, but that could be because it hasn't scanned the block containing the transactions where I moved BTSX into my wallet.
The client wavers between "No connection", syncing with the block count ticking up, or syncing correctly.
Usually I avoid keeping any coins on an exchange, but I'm starting to really consider it. I don't know about the rest of you, but I get extremely stressed out when I see a zero balance in my wallet, even if I've backed up my keys (which I have.)