Could be a couple of issues.
One is the config file is hosed.
Try going to:
Control Panel » Feature Settings[Tab] Attachments.
Use the test link and verify that all the info is correct in the other fields. And selct submit even if they are correct
But it sounds like this may be a gallery issue.
So first check:
Control Panel » DB, Paths & URLs and check you path settings for
ImageMagick Settings .
Then goto:
Control Panel » Gallery Settings
Again make sure all the settings are correct and select submit even if they were already.
There are other settings but at his point in time we would need more info on what type of attachment it is and if it is a gallery forum.
