It is likely that hippo's message above gives the right explanation, but I can tell you that I met a similar problem with a (DBI-Oracle) script that worked perfectly under my user and did not under the crontab (i.e. root user) because of environment variables being defined differently. I wasted almost a full day figuring out what the problem was, quite a poor performance if you think that I originally wrote the whole script in 2 or 3 hours.