Dear List!
I have searched for this problem in the archive, but found none to help

At one place, where they were using my Java program for a while, an
error appeared:
org.Firebird.JDBCFBSQLException: GDSException
unrecognized transaction

I'm using Firebird 1.03
and UNICODE_FSS database and am setting the lc_ctype parameter to UNICODE

The prepared statement with which this error occurs (this
preparedstatment was error free for dozens of times):

getweekdata=conn.prepareStatement("select "+
"data_id,data_owner,data_date,data_time,data_duration,data_msg,data_note,data_link,data_type,data_responsible
"+
"from data "+
"where data_owner= ? "+
"and data_date>= ? "+
"and data_date< ? "+
"and deleted=0"
);

(data_owner is varchar, data_date is date...)
I'm setting the preparedstatment the following way(where g is a
gregoriancalendar):

if(owner!=null) getweekdata.setString(1,owner);
else getweekdata.setNull(1,Types.VARCHAR);
getweekdata.setString(2,""+g.get(g.YEAR)+"-"+(g.get(g.MONTH)+1)+"-"+g.get(g.DAY_OF_MONTH)+"");
g.add(g.DATE,7);
getweekdata.setString(3,""+g.get(g.YEAR)+"-"+(g.get(g.MONTH)+1)+"-"+g.get(g.DAY_OF_MONTH)+"");

Executing it:
pst=getweekdata;
ResultSet rs1=pst.executeQuery();

When error occurs, I also write out the PreparedStatement, which was
the following:
org.firebirdQL.JDBC.FBPreparedStatement@bc8e1e

No what could have happened?
Rebooting etc doesn't help. And it was working fine before :(
Thanks!
John