Some have experienced similar problems after installing IE8.
Try this:
Open the Default Programs applet, which you can access either from
the Start menu or via the Control Panel, then click the first item:
"Set your default programs."
After a few seconds, a list of programs comes up. Click on "Windows
Mail". If it doesn't respond with "This program has all its defaults"
then fix it by clicking on the option indicated by the first green arrow.
Then repeat the above but do it for Internet Explorer.
--
Gary VanderMolen, MS-MVP (Mail)
"ZoCo1709" <(E-Mail Removed)> wrote in message news

21F817C-E808-4BD6-8ECD-(E-Mail Removed)...
> When I try to open a file (Word, Excel, pdf) directly from Windows Mail
> without saving the file, the associated program opens then I get an error
> message saying that the file C:\Windows\System32\<filename> could not be
> found. Check the spelling, blah, blah, blah ...
>
> Can anyone help explain why this just started happening and what I may need
> to do to correct it.