black vertical box viewing in test results

In test results I have a vertical black box viewing on the right hand margin which is blocking approx 20mm of the html email. This is only for Outlook 2003/Outlook Express 6 and Windows Mail, all the other accounts do not have it. It looks like it is a viewing 'block' where the email account is not viewing past that width (or where advertising might be). There is no extra scroll allowance to the right or down to view past the snapshot in the test result, though it looks like most of the email will view apart from that RH margin.

I have tested externally to Outlook Express and it viewed perfect, so only in the CM result snapshot is it showing this black box on the right hand side. I have checked my code and the 'wrapper has a bgcolour of white assigned.

Any ideas why this would happen, or how to correct it?  I am not sure if this is just a issue when the snapshot was taken.

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