FTP (proftp) / MAC Issues

We are on
Centos4.4 X86_64
WHM 10.8.0
Cpanel 10.9.0

We have tried switching between proftpd and pureftpd. Neither solutions work well for MACs or IE's trying to ftp into an account.

We are now on Proftpd.

When MAC users log on to a particular FTP account using Safari/Finder, they cannot upload anything anywhere; when they try to add files, they get an error saying that they do not have permission to write. However, many FTP servers do allow MAC users using safari/finder to read/write.

It has also been reported on some Windows machines by clients that they have troubles uploading files to the FTP server.

These problems do not occur with dedicated FTP programs such as CuteFTP, Fetch, etc.

Please advise