Can you post (a) a URL for one of the documents  when you click it from the
library (i.e. when it works), and (b) one of the URLs that when clicked,
results in a 404?

Here is the url https://site/xxx/xxx/SiteA/SiteB/Sept%2016,%202008.doc

Which one of the two is that, the working URL or the nonworking URL linked
from the DataView?

Also, I understand your desire to hide sensitive information, but would it
be possible to represent the folders with something a bit more unique than
"xxx" (unless of course those two names are identical)?

The URL - it appears to be going to the correct areas and is showing
me the document just fine in my web part - this link  is getting 404
error -
https://sharepoint.com/sites/sbeaware/mgmt_sr/JR_Mgmt/Sept%2016,%
202008.doc

Another words the URL is going to the correct places / mgmt_sr (this
is Site A in my description) / JR_mgmt (is Site B)/ the document name
is the same name as in Site A.....why then is it creating the error  -
I selected the correct for and field type as hyperlink - should I
check in hyperlink options?

When I go into Parameters I see the URL and all seems fine when I
select Save I get > The list  htat is referenced here no longer
exists. > I see the items in the web part ....

Link from site  A
https://sharepoint.com/sites/beaeaware/mgmt_sr/Status%20Reports%
20515/Sept%2016,%202008.doc

404 Error >
https://sharepoint.com/sites/sbeaware/mgmt_sr/JR_Mgmt/Sept%2016,%
> 202008.doc

it appears the List(Status Reports 515) I am trying to get the
docs from is not in the link  in Site B above - I don't understand the
data shows in my web part -

I have checked and I see the data  soucre in data source library  as
being linked...(mgmt_sr) and the library shows up also...Might I
check something else - or I will try to log in as administrator -

The Url that give an error  has a comma in it. Try remnaming the document to
sept162008.doc

Windows supports long filenames (up to 255 characters) and these can contain
any characters apart from the following: ? [ ] / \ = + < > : ; " , However,
the document libraries in Windows SharePoint Services have a subtly
different restricted set: ? " # % & * : < > \ { | } ~ and so any filenames
with any of these characters will be rejected as you try to upload them into
SharePoint. The obvious one is the "&" which is a quite legitimate and quite
common character in filenames but can't be uploaded into SharePoint. There
is no fix - you just have to rename your files. Additionally, the following
characters may not be used in Windows SharePoint Services site  NAMES: \ / :
* ? " < > | # { } % & " and site names may not START with the _(underscore)
character. The use of the parentheses ( ) should be restricted. Althought
allowed for Sharepoint naming, hyperlinks containing these characters may
fail.

The comma is included in both URLs, so it can't be the problem (though I'd
echo your call to remove it from the filenames); if it were, we'd see a
malformed syntax error  rather than a 404, which seems to be happening
because the link  is going to a library  that doesn't contain the document.

When I go into parameters and check the links - when I close
it I get this > The list  that is referenced her no longer exists <
could this be the problem - not sure what to do???? I really
appreciate you help on this as its driving me crazy because I did it
before with no problem.....

what is odd about this is we had a problem on Tuesday with the site
going down and I had prior to this had the list working properly -
after we restored the site  the site page for Managers would not come
up - I then opened  SPD and renamed the default page and then set the
renamed working page to the default page aspx - then I went back to
add the list via SPD as mentioned - The link  it appears is not
showing that I am going to -

I'm not sure exactly what went wrong -- I'd probably have to poke around
a bit before being sure about that -- but that does sound fishy. Was
anything renamed after the restore?

If you're saying that you created the DataView page *before* the
crash/restore, might you have more success if you created a brand-new page?

I recreated this data  view again - when I go into Common Data View
Tasks - Sort and Group - it tells me > The list  that is referenced
here no longer exists. But the data is showing  on the
webpart....

Is there an easy way to remove the linked  data source and then
re-create?