CiviCRM Community Forums (archive)

Just an FYI - solution below!

Attempted installs (2 different sites) of CiviCRM 4.2.6 in Joomla 2.5.8, PHP 5.3.17, MySQL 5.1.65 produced one of either message, depending on browser:
a) Fatal error: Allowed memory size of 50,331,648 bytes exhausted (tried to allocate 29350638 bytes) in /home/abcde/public_html/abcde.com/subs/site1/libraries/joomla/filesystem/archive/zip.php on line 453
b) Your PHP version is missing zip functionality. Please ask your system administrator / hosting provider to recompile PHP with zip support.
Had my host check on the "increase PHP memory" solutions, all confirmed available, yet no change in the results (i.e., fail). 

So, searching the "manuals" and forums, here's what eventually worked, in less than 2 minutes:
1. unpack the *_alt.zip package to the /joomla/tmp folder
2. delete /administrator/components/com_civicrm
3. delete /components/com_civicrm
4. add the extra memory line(s) (check with your provider if you don't control) to .htaccess
5. extension manager > install > Install from Directory (i.e., as unpacked in step 1 above)

I think the "alt" package was the real answer to my initial install experience, hopefully, your's is same for these errors.

Adios,
Bob