Does it happen on all machines? What OS? How much memory? Be sure to run AdAware and virus check, use MSconfig to turn off any unnecessary programs from loading at startup. If its only happeing on one machine try uninstalling and reloading.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .