This is surprising. It sounds like a server configuration problem to me. Actually we have translatable text in our plugin and it sounds that the fact of loading our plugin just increase the memory usage which is logical. I would advise you to just increase this value as you can. Doubling it can be a good idea.
Try to do so using a command like the following, straight in the wp-config.php file for instance:
You can also do it in your php.ini depending on what your host provide:
; Maximum amount of memory a script may consume (128MB)
memory_limit = 128M
I'm not sure that's is such a good idea to change the access rights of the mo.php file :). you're better off leaving it as it was 755.
Hope this helps,