Explanation of the Causes of the White Screen
The issue appears to be that when a page is loaded, and the script tries to load one (or more) additional files to perform sub-tasks, the system runs out of allocated memory.
The reason this is happening is because those of you encountering this issue are very likely running your site on an overselling host. This means that the host you chose sells sites with "unlimited" stuff, such as bandwidth, or disk space. The truth is that nobody could actually afford to sell "unlimited" everything (or anything). Hosts need to pay for expenses and make money. The host that you chose may advertise "unlimited", but in reality, they have severely limited your account, because they put far too many "unlimited" accounts on the same physical, or virtual, machine. They then apply "hidden" limits, and shut your forum down, when your usage exceeds these limits. Even though you are, therefore, meant to have been offered an "unlimited" service, you have not.
It is important to realise that there is a limit to how much memory a given script can access, and that every host has a limit like this. A real host, however, has a reasonable amount, and will not put far too many accounts on a single server such that they overuse the available resources, and a real host will discuss how much you require if you truly need to exceed that amount.
In your case, the host has set this limit low. So low, in fact, that the package manager cannot load Subs-Post.php to process the BBC tags in the readme file of the mod. If that inclusion is bypassed, the script next chokes on the loading of Subs-Package.php, which cannot be bypassed because that file contains the instructions needed to process the Mod package.
How to Solve the Problem
You now have two choices:
- Ask your host to increase your available memory.
- Switch to a non-overselling host. There are a large number of those hosts listed in our Hosts and Hosting boards
These hosts may be slightly more expensive than the one that you originally chose, but, as is often the case, you do get what you pay for.