I recently found that I had to many text messages in my sent folder on my nokia e51 phone. This caused the cellphone to not display new messages as it didn't want to show them unless there were fewer messages in the sent folder than the limit. Each time the phone was turned off and on again this was done and the text messages arrived, but this was to much work to do.
There are 2 fixes for this:
Increse the limit on how many text messages you can have in the sent folder:
select No. of saved msgs.
enter the maximum: 999
If you have reached 999 messages the limit cannot be increased anymore therefore the messages in the sent folder needs to be deleted or moved. If you don't want to delete the messages do the following:
select My folders
select New folder
go back to Messaging
select Mark/Unmark and Mark all
select Options again
select Move to folder and select the folder you created.
Thus you archive your messages and leave space in the sent folder.