To expand on xav0989's comments, you can, in Firefox, use Firebug's "Net" tab or, in Safari, use the Web Inspector's "Resources" tab to check that all the page components are loading.
When it comes to units, use whatever is most natural for the content type. ems for text, px for images and movies, % when sizing or positioning relative to the viewport (the window). Because they (typically) use vector graphics, flash movies are more flexible in terms of which units you can pick.
Also, posting screenshots of the correct and broken layouts will be very helpful in determining what the page is supposed to look like ("all wrong" and "all over the place" aren't very descriptive; best to save your 1k words and post a picture), and hence what might be causing the page not to look like that.