[kh99]

Yeah, using var_dump() will output whenever the code is run, and the way vbulletin works is it builds all the output into a string then sends it at the end, so the result would be that something you print out will come out before anything else and likely cause errors as well. Sometimes for debugging i do something like var_dump() a variable then call die, and you'll get a page with nothing else on it, but of course you only want to do that on a test forum. You could also open a file and write stuff to it, then look at the file after. Anyway, if you do decide to try to display that, $hook has all the code for that hook so you only need to var_dump it in one of the plugins.

You might want to temporarily put all the code in one plugin and disable the others, just to rule out the multiple plugins as a potential source of the problem.