Playback and rendered video jumps up and down regularly and minutely

Question

A number of the sequences I've edited have a minute but noticible up-and-down movement.  For example, see http://www.youtube.com/watch?v=hely09sD6gY  You'll notice that only the video image moves up and down, not any of the still images or the StudioCrasher watermark.  I initially thought it was the source video I'd imported, but on a more recent project I've noticed that it also does it with footage from a secondary video camera. 
I also note that this doesn't happen on the original source video in Premiere, just in the edit playback and in the exported video.  So, it has to be something in Premiere. 
I've tried everything, including searching endless discussion boards, but I can't come up with a solution or a work-around. 
Any ideas? 

Answer 1

Thanks John -- okay, here's my answers:
What version of Premiere Pro? Include the minor version number (e.g., Premiere Pro CS5.5 with the 5.5.2 update).
Premiere Pro CS5.5 with the 5.5.2 update
Have you installed the recent updates? (If not, you should. They fix a lot of problems.)
Software up-to-date.
What operating system? This should include specific minor version numbers, like "Mac OSX v10.6.8"---not just "Mac".
Mac OSX v10.7.5
What kind(s) of source footage? When telling about your source footage, tell us about the codecs, not just the container types. For example, "H.264 in a .mov container", not just "QuickTime".
Canon Legria HFG10
Type: MPEG Movie
File Size: 1.9 GB
Image Size: 1920 x 1080
Frame Rate: 25.00
Source Audio Format: 48000 Hz - compressed - Stereo
Project Audio Format: 48000 Hz - 32 bit floating point - Stereo
Average Data Rate: 2.9 MB / second
Pixel Aspect Ratio: 1.0
If you are getting error message(s), what is the full text of the error message(s)?
N/A
What were you doing when the problem occurred?
N/A
Has this ever worked before?
N/A
What other software are you running?
It occurs regardless of what else is running or not. 
Do you have any third-party effects or codecs installed?
No
Tell us about your computer hardware. Be especially certain to tell us about third-party I/O hardware (e.g., AJA, Matrox, Blackmagic, MOTU).
Processor  2.7 GHz Intel Core i5
Memory  12 GB 1333 MHz DDR3
Graphics  AMD Radeon HD 6770M 512 MB
Are you using Mercury Playback Engine GPU Acceleration?
Not that I'm aware of. 
Does the problem only happen with your final output, with previews, or both?
Preview window and final output.  Not in source window. 
Screenshots and sample movies are often very useful in showing exactly what you're seeing, and can thus make getting an answer faster and easier.
Example: http://www.youtube.com/watch?v=hely09sD6gY