ls -al /home/users/sharedspam/.spamassassin/ total 19092 drwxrwxrwx 3 root users 1024 May 11 17:17 . drwxr-xr-x 6 sharedsp users 1024 May 20 2003 .. -rw-rw-rw- 1 sharedsp users 0 May 20 2003 auto-whitelist drwxrwxr-x 2 sharedsp users 1024 May 20 2003 bayes
Try removing that bayes subdirectory.
I've seen SA have trouble in the past when people have a directory by the name of the full bayes_path. I think SA tries to open ${BAYES_PATH}* and make sure that they are all files with read permissions. Since the name "bayes" will match, it can cause SA to fail.
