Are you viewing the report in SSRS using Firefox or Safari? There are known rendering issues with those browsers:

http://sqlbiconfessions.wordpress.com/2009/12/01/ssrs-reports-rendering-issues-with-firefox-and-safari-browsers/

See if you get the same view of the report when...

Is your colleague using Firefox or Safari? There are known issues with SSRS's rendering using those browsers:

http://sqlbiconfessions.wordpress.com/2009/12/01/ssrs-reports-rendering-issues-with-firefox-and-safari-browsers/

You could perhaps try using an expression in Properties -> InitialtoggleState (near the bottom) for this report item, something like =IIF(Parameters!Month.Value = 1, False, True).

Doug

My experience has been that pdf respects formatting better than Excel, particularly with narrow margins. I've had several instances where PDF will properly fit on a page but Excel...

We had a similar issue at our workplace and it was tracked down to the two cluster servers not having the same configuration. See if your clustered servers are on...