Here's a list of problems/issues so far that I've had with my 6230, and some workarounds. Maybe someone else has had the same or similar problems...
Nokia 6230 v4.43 Cingular Wireless
Sim card gets rejected many times when phone turns on.
Phone turns off and on randomly (guessing this is from the ATP 1 gb mmc card)
Can't allocate more space to the applications folder (still space on handset memory, however only alotted 1.5 mb space for apps)
Can't set folder to install applications to in PC Suite.
Bluetooth sometimes turns off randomly when connected, and only way to turn it back on is by turning off and taking the battery out, then powering on again.
Music player can only play mp3s or aac files directly in the MMC card, not in subfolders.
Max file size allowable for media player to read (i have 1 gb of memory on the MMC, but the player can only read up to the file size of 101 songs).
Handset has problems reading SIM card sometimes...sometimes can't read the whole phonebook (half or more entries missing). Had to power the phone off and on again to see complete phone book.
When playing a 3gp video file in the media player, and when sound is on mute, if you push the red "hang up" button to exit, sound plays for a split second (found this out trying to watch a video in class...scared me with the sound).
Not able to turn off time screen saver.
Cannot set the message alert tone to an audio file within a subfolder of the MMC card (even though it states that it is set, it reverts to the default nokia tone anyways).. Had to move my mp3 file i use for the message alert tone back to the Music folder on the handset.
Can't think of any more issues/problems i've had with the 6230 at the moment under v4.43 firmware. If i think of anything else, i will post it here.
Hope this helps some people, either in their purchase decision, or with current problems/issues.