Well the simplest way of solving this is to run
sudo apt-get install php5-gd
That will install the necessary libraries that you need to keep continuing. If you are in windows then you need to go to your php.ini and uncomment the following lines
;extension=php_gd.dll
;extension=php_gd2.dll
[just remove the ; to uncomment them]
Hope that solves your image issues.
Well here are some quick ways of solving your “cron not working properly issues in drupal”
It has a semaphore which blocks the cron running, in my case the PHP script ran for too long and ate up too much memory. I needed to modify my php.ini to ensure that it could take up more memory.
Another issue was that you needed to delete a certain variable in the Drupal database, use the following for a quick resolution to the problem.
DELETE FROM `variable` WHERE name = ‘cron_semaphore’;
DELETE FROM `variable` WHERE name = ‘cron_last‘;
Another way is to install the devel module and delete the above variables from the database using the UI.
Hope this helps.