tar: Error is not recoverable: exiting now

I would try to unzip and untar separately and see what happens:

mv Doctrine-1.2.0.tgz Doctrine-1.2.0.tar.gz
gunzip Doctrine-1.2.0.tar.gz
tar xf Doctrine-1.2.0.tar

It's possible your tar file is not zipped. I just had this same error, but all I had was a plain old tar file. So try just removing the z from your flags. The z flag unzips your tar file as well as whatever other commands you requested with other flags. i.e. try:

tar -xvf Doctrine-1.2.0.tgz

Notice I removed the z from -xvzf

Try to get your archive using wget, I had the same issue when I was downloading archive through browser. Than I just copy archive link and in terminal use the command:

wget http://PATH_TO_ARCHIVE