Two questions:

1) What authentication method are you using?

2) Are you seeing the actual browser error  message? Make sure by going to
the Tools menu in Internet Explorer, clicking Internet Options, and going to
the Advanced tab. If "Show Friendly HTTP Error Message" is checked, be sure
to un-check it, save your settings, and try again. Post the full text of
the error message if you get more.

Authentication is via Active directory/windows

So far one of the erros I get is below:
<
No item exists at
portal/.../DispForm.aspx?ID=9. It may
have been deleted or renamed by another user.

Web Parts Maintenance Page: If you have permission, you can use this
page to temporarily close Web Parts or remove personal settings. For
more information, contact your site administrator.

Troubleshoot issues with Windows SharePoint Services.
>

I have double checked the file  exists. if i copy the link  and paste
it under my login it works fine.
Also the email  that i get from the system says the task was assigned
but i do not have permission to view the task. It only after i clcik
on request access  which then give me access to the entire site under
under restricted access (which is not so restricted) as i can view
the entire site now.
That i get access to the workflow  and doc library from which the
request came.
says

When a user  gets that specific  error, it means that the user does not
have access  to the list item. It sounds like you need to go ahead
and give the appropriate users access to the list, before trying to
send links  to them.

If you don't want to give them access to the entire site, you can
just grant them access to the specific list(s) that they will need to
go to.