First copy all the .cr2 files using Canon's EOSViewerUtility. You may have to drag the whole folder to your system local drive. Then open the cr2 files from the copied folder from CS2. Should open without any flaw. This is how I edit raw files. If it still gives you the same error, try opening the cr2 files with "RawShooter essentials 2005" (A freeware). If the same problem persists, I guess the cr2 files may have been corrupted.
Hope this helps you.
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