Most likely the reason for this is a very long string in the field that is pushing the table wide. For example. The following string is going to push the table width because there is no space for it to break onto another line.
slkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsjslkdjflksdkldsjfkdsj
Is this the case? If so you are going to need to clean up the text in the offending field.
Or, something I have done in the past is to cut off the field to 50 or so chars and add a link at the end with the the text of "....more"
Clicking that will show you the full text in a seperate window so it doesn't break your layout.
[edited by: Demaestro at 4:11 pm (utc) on June 1, 2009]
[edited by: engine at 8:03 am (utc) on June 3, 2009]