Unable to open file on cifs drive

Hello,

I'm unable to open any files on a cifs drive with Quanta 3.5.10 (Suse
11.3 / KDE 4.4.4).

Error Message:
The file
file:///mnt/atvieltvm04/E/Intranet/dbfft/Auswertung/bericht_01.php could
not be loaded, as it was not possible to read from it.
Check if you have read access to this file.


However, I can open/save the same file with kwrite. 
AND what's strangest: Quanta can create a file on that drive, but once I
close it, I cant open it again!

Any suggestions what's wrong?

Gerhard