attachment upload restrictions?

[airbrushtutor]

My users have started telling me that the forum is telling them they can't upload further attachments because they have exceeded their upload limit.
I have set filetype limits but all attachment upload limits in the usergroup manager section are set to '0' for unlimited. Why then is it saying this to them?
any help appreciated thank you:confused:

[kh99]

There's also a total attachment space setting in the settings under Message Attachment Options. Do you know what the exact error message is?

[airbrushtutor]

Hi kh99 - thanks mate, i did check that but it''s also set to 0. They are telling me it says that they are unable to upload the attachment because they have reached their upload limit. There are no limits set to my knowledge? I've set filetype limits but have set the rest of the attachment limits to 0. I must have missed one but i can't find it? or is there a default limit somewhere?
I've changed the usergroups options to allow unlimited and the forum permissions to allow unlimited. I'll ask them to give me a screen shot.
any help would be appreciated