check out the settings for that file in the finder: Select the file, then type cmd-i for 'info'. At the bottom of the appearing window, You'll find the priviledges/permissions. You (the owner) should have read/write permissions
The next (or the first..) step would be to repair permissions using disk-utility (hope, the name is correct, don't have an english system here). I'm puzzled by the message when You try to update Filemaker..
Thanks Markus... Just tried this - no luck as Everyone's permissions couldn't be changed.
Now trying my disk utility...
there is a problem with the current user - 'unknown'
You can set the permissions to read/write for everyone - but this seems not to be the real problem. Maybe disk utility (repair permissions) will help. Ask Your system manager...