Yea sadly people abuse this and I see it on alot of sites!!
I guess its understandable Virge why you have it limited to staff only....
What ya could do is take the reg long time members (In the reg member group (Senior Member for example)) who dont do that and allow them attachments.. (They wont cause problems for you)
I dont know how much space you have on the computer running this site,that has to be considered also........