Error and a question

Every time I post or update, I keep getting the following error:
Fatal error: Call to a member function on a non-object in /web/sites/stephenv/stephenvandyke.com/wp-includes/class-xmlrpc.php on line 760
I assume it has something to do with pinging, but I haven’t dug around in the code just yet.
…
I also want to know how I can differentiate between the front page (or category/month pages) and a post… I used to be able to do a if(!$p), but that is now broken or gone since I upgraded to 1.2b. I was using this to make sure robots only indexed posts and nothing else, it would help to be able to use this for other purposes too. I hope it’s simple.
TIA