fist thing i thought of is sent MMS, you said you had checked messages so
its probably not that, could it be that the amount of free memory is just
incorrect, ir can you only save 0.6MB more data, thats worth a try.

matt

Assuming Windows is your environment.

Try the following :-

Do a Backup. This, as a side effect, it reboots the phone (it fixed quite
a few problems I had on my phone initially)

Check the memory. If it's still missing, do the following :-

Open the Backup/Restore application
Find out where it is storing the backup archive (it shows on the right
somewhere)

Open that file using winzip (ignore the fact it has not got a .zip suffix
so change the suffix to 'all files' rather than '*.zip' in the open
dialog)
Extract it all out to a temp folder. There is a Text file (I forget
the name, something like file list) which gives you a relationship between
the file numbers and the file names as stored on the phone. It also gives
you sizes. Have a dig through this list to find out where the space has
gone :-)

Worst case scenario is to delete the culprit files out of the ZIP archive
then do a restore - I would not do this unless you have an unmodified zip
lying around that you can re-restore from in case you delete a wrong file!

...Lyall