Group permissions and Unix servers

I use Smart FTP to transfer files to and from storage held on my ISP's Unix servers running Apache. From time to time, uploads fail due to the error "Disk Quota Exceeded" even though there's plenty of space left. My ISP says that this is down to a "conflict in the group user permissions", mutters something about Frontpage, resets group permissions, and all is well (for a while).

What I like to know is, is problem likely down to my ISP, or am I maybe causing the problem by not configuring Smart FTP correctly? When I'm writing up folders, I just drag them straight in. Should I be doing something with the group or user ID checkboxes on folder/file properties?

Can anyone shed some light on this ('cos my ISP can't/won't!) ???