It can take more than hour to synchronize. Does "X weeks behind" change? – John T – 2014-01-26T03:53:00.413

It has been a few hours now and it still shows "No block source available...155 weeks behind". – JLP – 2014-01-26T17:18:49.637

For your first question, I would suspect that you haven't put your bitcoin.conf in the place where the Bitcoin client is looking for it. The correct folder should already contain files named like debug.log, peers.dat, and several others. – Nate Eldredge – 2014-01-26T19:03:29.920

@NateEldredge I have bitcoin.conf in the User/MYUSERNAME/AppData/Roaming/Bitcoin folder. This folder has the peers.dat, wallet.dat, db and debug files as well. There is no debug.log file. Do you have any ideas on why it is showing "No block source available"? – JLP – 2014-01-27T04:21:03.947

Typically this means it is not able to connect to any peers on the Internet. One possible cause is bad proxy settings, which is why I wondered if it was using a bitcoin.conf different from yours. Otherwise, could there be firewall settings or something similar preventing the application from communicating with the Internet? – Nate Eldredge – 2014-01-27T05:05:24.350

@NateEldredge It did not have a bitcoin.conf file. I created it. Bitcoin-QT is running in Windows 7, which is running in VirtualBox, which is running in my Mac OSX. There seems to be no issue with any firewall in Windows 7 as my browser works fine. I have LittleSnitch running on my Mac, which tells me if a program is trying to access the internet. It told me that Bitcoin on my Mac and a program on Windows tried to access the internet, which I allowed. On my Mac, my Bitcoin-QT (in testnet and mainnet) synchronized fine. On Windows, Bitcoin-QT for mainnet, but not testnet, can synchronize. – JLP – 2014-01-27T17:17:31.200

That's very strange. My only other idea would be to look at User/MYUSERNAME/AppData/Roaming/Bitcoin/testnet3/debug.log and see if there is a helpful message. – Nate Eldredge – 2014-01-27T19:15:14.947

@NateEldredge debug.log does not exist, but User/MYUSERNAME/AppData/Roaming/Bitcoin/testnet3/debug does. It has a lot of messages. Do these provide any clues?

2014-01-26 01:15:49 trying connection 93.93.135.12:18333 lastseen=149.6hrs 2014-01-26 01:15:51 No valid UPnP IGDs found 2014-01-26 01:15:51 upnp thread exit 2014-01-26 01:15:54 connection timeout 2014-01-26 01:15:54 trying connection testnet-seed.bluematt.me lastseen=0.0hrs 2014-01-26 01:15:59 connection timeout 2014-01-26 01:16:04 trying connection testnet-seed.bitcoin.petertodd.org lastseen=0.0hrs – JLP – 2014-01-28T05:33:39.937

I also have the same issue @NateEldredge . But proxy isn't a problem for me. I tried by changing the proxy several times but its of no use ( I use college internet ). It works fine when I run it using my mobile data. I don't know why. I opened a question for the same with clear explanation and debug logs here, https://bitcoin.stackexchange.com/questions/52906/unable-to-connect-to-peers-nor-synchronize-the-network