applications does not write

Application running on a local network does not write.
The application runs on a Novell network (NDS6), one part a so called E_LAN,
for students only, and a A_LAN for administrative purposes. (Windows XP as
system)
Students use it to sign up; the application places them in groups, and on lists
/ waiting lists. The information is written in a .txt file (CSV) . So far this
(reading and writing) works fine.
I want to make changes in the lists. The problem is that I can not write these
changed information to the text-file, the application seems to 'hang.' This
happens only if the administrator wants to save the changed information to the
txt-file on our local network, not on a stand-alone (Windows XP).
The code for both paths, reading and writing is the same, the path + file is
Q:\\Opgaven.txt
Some code, to write to the file:
"
String abspad = fil.getAbsolutePath();
FileWriter fw = new FileWriter(abspad);
infovector = geefVector();
for ( int i = 0; i < infovector.size()-1; i ++ )
{
 String elem = infovector.elementAt(i).toString();
 uit = uit + elem + "\n";
 }
 fw.write(uit);
 fw.close();
 pta.appendText("\n" + "Gegevens goed opgeslagen");
}
catch (Exception ex)
{
 String iks = "" + ex.toString();
''
The exception is:
FileNotFoundException: Q:\\Opgaven.txt

I also tried a hard-coded path.
In what direction I have to look for a solution for my problem ?
Is the file open, so writing is impossible?
Is it the 'wrong' writer ?
Why this works on a stand alone and not in a intra network?
Any help would be great.