I've had two occasions now where my Boss has blocked my transfer to another department. Applying for intracompany jobs is supposed to be confidential, but as a SVP she finds out. I know she loves my work, but does things to prevent me from moving up within the company. I'm bored at my current job and would like to do something else. What should I do?

You must be doing a great job and she could be wore out with supervising less than able people (kindest thought) or her motivation could be that you are making her look good to her supervisor (not so kind thought) or a lot between.
Could you talk to her and see if you could assume additional duties that would be more challenging for you so you can stretch your abilities a bit? Short of that getting some educational courses could lead you to other work that you would be happier with or anything between. Good luck

Could you be a bit more specific, how did she block your transfere?

Been here 4 years with good rep. Boss's best friend had a job opening. I didn't even get a courtesy interview with CEO. Ran into CEO in elevator and told him I applied. He said he'd look into it... he likes me. Never heard a word.

Second time... job opening in my department. She knew I wanted the job... she made it part time so I couldn't apply (I need my insurance benefits).

If you are stuck in your own company often you have to consider going to another company for promotions.

Unless you are not being hired because of a protected class, race, religion or other reasons, they can not promote if they don't want to.

You need to talk to HR about this.