If you encounter problems, for example when activating a plugin, like a white page or an error like:
Fatal error: Allowed memory size of xxxxxxxx bytes exhausted (tried to allocate xxxx bytes) in …..
then you your solution should be simple and it will be easily solved by your hosting provider by increasing your PHP memory_limit directory to 128MB recommended.
Read the article below for more details on how to change the PHP settings:
http://seventhqueen.com/blog/code-snippets/increase-php-memory-limit-in-wordpress.html
