I'm seeing this behavior in both the word processor and the spreadsheet section.  

When I try to open a file by double clicking on it in Windows Explorer or by
right clicking it within Notes, then choosing "Launch...", I get a series of
dialog boxes that say (example uses a file inside Documents and Settings):

Error loading file ...

For example, the full path to one file on my system is:

C:\Documents and Settings\jmsmila.000\My
Documents\USBank\Projects\ConsolidatedSignon\POC2_Expectations_Roles_Timeline.xls

The error that I get is:

 ///C:/Documents:
C:\Documents does not exist

When I click on OK, I see:

Error loading file
///C:/Documents%20and%20Settings/jmsmila.000/My%20Documents/USBank/Projects\ConsolidatedSignon\and:
C:\Documents and Settings\jmsmila.000\My
Documents\USBank\Projects\ConsolidatedSignon\and does not exist

After failing that, the system tries to build a valid path to the document a
couple of different ways before giving up and failing silently.

However, if I open OpenOffice first, then choose the document through the normal
File -> Open dialog, it is successful.

So far as I can remember, this is a change in behavior since beta 2.