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To fix it, try resetting Web settings in Internet Explorer. If this does not resolve the issue, set IE as the default browser.
also if that doesn't fix it go a step further
In IE Click Tools, click on the Advanced tab, Reset Internet Explorer Settings click the Reset button at the bottom
then if that doesn't work try this
on the start menu -clicking Default Programs
clicking Set program access and computer defaults.
instructions here
http://windows.microsoft.com/en-US/windows-vista/Change-default-programs-using-Set-Program-Access-and-Computer-Defaults