This may be related to this issue:

http://www.openoffice.org/issues/show_bug.cgi?id=84264

Steps:
1) Create a plain ASCII text file with LF line endings only.
2) Start OO Writer.
3) File -> Open
4) Choose the text file.

Expected: File is opened in new Writer document; ASCII Filter Options dialog
possibly displayed.

Actual: File is opened in Calc; CSV import dialog is displayed.

Workaround: Choose "Text Encoded" filter when opening. The default "All Files",
as well as "Text" and "Text Documents" produce the unexpected behavior.

Comments:

  - Opening files should take the currently running OO component into account
when determining the preferred behavior, when more than one OO component may be
appropriate for a given file type (e.g. when opening .txt files while currently
using Writer vs. Calc). 

  - The filter descriptions relevant to .txt files are ambiguous. Currently,
when in Writer mode:

     * All Files (default) - Opens .txt, LF-endings in Calc.
     * Text Documents - Opens .txt, LF-endings in Calc.
     * Text (*.txt) - Opens LF-endings in Calc.
     * Text Encoded (*.txt) - Opens in Writer.

    A clearer behavior may be:

     * All Files - Opens .txt in current application (this is the default
filter; it is reasonable to guess at what the user likely wants to do).
     * Text Documents - Opens in Writer, always.
     * Text (*.txt) - Opens in Writer, always.
     * Text Encoded Data (*.csv;*.txt) - Opens in Calc, always.

  - I have heard that a similar issue exists on Linux. I have not tested this.

  - OO's current logic when determining which application to open a .txt file in
is somewhat flawed: "if CRLF then Writer else Calc". Line-endings should not be
a criteria in determining whether to open a .txt document in Writer or Calc.