Update: it's not the plugin - it's a memory problem.
I was able to install wp-e-commerce only after doing each of the following (I tried this MANY different ways before getting it to work):
1) create a file called php.ini (using a text editor) and adding the following:
;; set memory limit for cache.php
memory_limit = 128M
...upload (FTP or cPanel File Manager) the php.ini file in 3 places;
- above the root directory
- in the root directory (public_html or www)
- and in the wp-includes directory
2) Add the following line below the opening
<?php tag in the file wp-includes/cache.php:
ini_set('memory_limit','128M'); // set memory to prevent fatal errors
(...yes it's modifying a core file, but it works!...just make a note of the modification)
After that, create an htaccess file for the wp-includes directory and insert the following directive:
3) Use a text editor to create a .htaccess file and add the following:
# set memory limit for cache.php
php_value memory_limit 128M
...upload the .htaccess file to the wp-includes directory.
Log out of admin, clear browser cache, login and install the module.
See the following for details:
I hope this helps...