I had a hell of a time installing lxml for python2.7 on centOs5.6. For some background, python2.7 is an alternative installation of python on centOS5.6 which comes with python2.4 installed.

it was bulit from source per its instrucitons

./configure
make
make altinstall

However, after about 20 hours of trying I managed to find a workable solution and was able to install lxml.

Until, I notice the following error at the top of the interpreter:

python2.7: /usr/lib64/libz.so.1: no version information available (required by python2.7)
Python 2.7.2 (default, Jun 30 2011, 18:55:26) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-50)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print 'Sheeeeut!'

this error is printed out everytime I run a script.

For example:

$ ./test.py
/usr/local/bin/python2.7: /usr/lib64/libz.so.1: no version information available (required by /usr/local/bin/python2.7)

the script runs flawlessly, but this error is bothersome. After some digging I have seem to believe I have a wrong version of libz installed, that it is either an older version or built for a different platform.

I'm not quite sure how, I've only installed libz through yum, as far as I know. Although, I can't quite remember every little thing I tried in my twenty hours of trying.

You may also be intereted in what my lib64 folder looks like, here is some information

$ ls -ltrh libz*
-rwxr-xr-x 1 root root  84K Jan  9  2007 libz.so.1.2.3
-rwxr-xr-x 1 root root 107K Jan  9  2007 libz.a
-rwxr-xr-x 1 root root 154K Feb 22 23:30 libzdb.so.7.0.2
lrwxrwxrwx 1 root root   13 Apr 20 20:46 libz.so.1 -> libz.so.1.2.3
lrwxrwxrwx 1 root root   15 Jun 30 18:43 libzdb.so.7 -> libzdb.so.7.0.2
lrwxrwxrwx 1 root root   13 Jul  1 11:35 libz.so -> libz.so.1.2.3
lrwxrwxrwx 1 root root   15 Jul  1 11:35 libzdb.so -> libzdb.so.7.0.2

notice: the items that Say Jul 1st or Jun 30th are from me. I had initially moved these files into a backup folder as they seeemed to be 1. duplicates and 2. had a date after/during my problems I alluded to earlier that I had with lxml

One inclination is to completely remove python2.7 and re-install. I think having it install to /usr/local/ was a poor default choice. However, without the make uninstall option being present it seems to be a time consuming task for a solution I am not quite sure would solve my problem.