'no application can be found' problem

[gregfripp]

i have a late iMac running 10.8.2 with no known problems
yesterday my mail downloaded as usual
and also my mail had some mail with leads to various sites
but when i clicked on them
a sign came up saying 'no application can be found' for the link
i have never had this problem before
i have just run disc warrior with no difference noted
does anyone know a cure?
greg, puzzled