Your ISP is the comapny that you get internet access from. They've had to block some of them to stop attacks from certain regions. Crossposting will be messed up as long as LJ is having trouble, unfortunately.

Do you remember the title of your story? I have the hoggywarty page open, so I can get the link for you. (Unfortunately, LJ is not working well for me - it occasionally loads, but it's taking forever and giving a lot of errors. Basically LJ is screwing up for most people, but more for some than for others.)