Yes, you can safely block that (I've done it myself). You can also safely unblock it if you prefer. Note that only administrators get the "Unblock" option. It would be even better if you had a seperate account for your administrative needs, rather than running as an administrator normally (nearly all viruses and spyware won't run if you aren't an administrator), but that's also something that takes a little work(and/or a helpful friend).