Config: NW65SP6, NBM 3.9, 3x23GB cache volumes on RAID 5, 4GB RAM, newer, dual-processor AMD box

I've a dedicated NBM 3.9 box that continually shows a yellow or red light in Remote Manager for "Available Directory Entries". I've removed all but DOS name spaces from the 3 cache volumes which freed up a bunch of directory entries but they were quickly consumed. and the lights returned.

I've not seen any performance issues on the box. It is a new server. I've been migrating 100-200 users a week from an old Squid box to this one. Eventually it will have about 1500 users on it (there are probably 500 on it now).

Any thoughts on why this is happening? So far it's more of an annoyance than anything else.