There is a known issue after updating to 5.0, that if you look at a page containing an iView island pointed at another page, the iView island page tries to resize its islands and fails, making them zero or negative height and width.
The following SQL script will reset the sizes of just these pages:
Set [Left] = null, [Top] = null, width = null, height = null where islandinstanceID in (
Select islandinstanceID from Production_Portal_PortalFx.dbo.PWPageIslands
where Pageid in (
where width like '-%' or width like '0%' or height like '-%' or height like '0%'))
Then clear the cache and visit the page that is the target of the iView island. It should resize properly.