ARGH!

Ever made an incredibly stupid mistake at work?  Well that's exactly what I did.  Last week I sent out the summer mailing to the parents and of course I read everything to make sure it was all correct - and OF COURSE I missed a mistake and it went out to families with an incorrect date!  It's so frustrating!  I decided when I went back to work from my maternity leave that while at work I would work really hard otherwise what's the point in being away from E-rizzle?  And of course my first week back from maternity leave I make a mistake (I knew everything was going too smoothly).
What do I normally do when I make a mistake?  Beat myself up about it - regardless of whether or not it was a big or small mistake.  And I always try to put things in perspective but still I beat myself up about it.  I don't know where this attitude of mine comes from.  When I was in school - the school I went to (I felt) was incredibly competitive.  And I'm the LEAST competitive person I know.  I can't watch game shows without having palpitations for crying out loud!  Plus I always felt a little inferior to everyone around me - whether people were smarter than me, or more athletic or more this or more that.  So I expect average from myself (probably why I've given up so many different hobbies).  It's hard because I know everyone makes mistakes but when you're trying to turn over a new leaf and then you just combust it's annoying & frustrating!  Plus I'm just waiting for this to come bite me in the tooshie!  Just you wait - it'll happen!
What are some mistakes that you've made??