Issues with the devel module After I install the devel module I can no longer configure any blocks, I get an internal server error. I uninstalled and the issue stopped, re installed and its an issue again. 

Furthermore, I cannot see the grey box in the lower left hand side of the browser where I can access all the variables available in a given page. This is the main reason for attempting to use the module. The module is successful in printing all SQL queries at the bottom of the page however. Any insight as to what might be wrong?

Update: I can also no longer uninstall the devel module from within the drupal backend, i receive the same error when trying to access the uninstall page, I will have to remove it manually from the file system

Update: Removed the devel module once again and problem is gone...
Based on your comment about the 500 error and the menu entry problems, I suspect that the problem isn't really with the Devel module, but rather with your server.

Take a look at your Apache error_log to see what is causing the 500.  Following the steps for fixing a WSOD may also help.

A total guess is that you are running out of memory, and this is happening during the menu rebuild phase when you have an empty cache.  Enabling the Devel module likely was just the tipping point and now you are seeing memory problems.  You can try increasing the memory_limit and see if that fixes things.  But, you really do need to look at the error logs and find the true cause of the 500 errors.