Khimberly
As per the thread title, the problem clips are XDCAM HD 422, yet you go on to state in your post that the footage was shot on an EX1 (which does not support shooting to that format). All very confusing. As Rafa notes, XDCAM EX codec support was added in FCP 6.0.2, and XDCAM HD422 codec support was added to FCP in version 6.0.3 … either way, if you are running FCP 6 then you need only connect your system to the internet and run the OS X software update app (second item under the Apple menu) and that should bring you all the way up to FCP 6.0.6 … and those clips should then be viewable / editable.
Cheers
Andy