utl_file problem on Solarsi 9i database

Hi,
I'm experiencing problem with utl_file database package on 9.0.1.4.0 Sun
Solaris database
I use a database stored package to write several thousands of files to
server machine using utl_file database package. It worked fine for few
months, but after last database restart, strange things begin to happen:
files are truncated ! I can't find the reason why files are truncated
(number of lines in files are not the same, nor their length in bytes). When
I rewrite program not to write several first lines, some missing lines from
the end of file appears !
I try to use dbms_output package to debug program and it seems to work fine
(every utl_file.put_line is followed by corresponding dbms_output.put_line:
all dbms_output.put_line are executed, but the file is still truncated for
several lines)
I'm not able to restart the database for some time, and I'm not even sure if
that will help
Can someone help please?
Thanks in advance:confused: