SMB server license not available?

[Dunalastair]

My network users are being denied entry and the sys log tells me that "no license avail for user xxx for SMB server 4.0"
The trouble is, I have 60 licenses on the server, but currently only 12 users logging in! (the rest arrive later this week!). I recently replaced this server (harware change) and re-installed from scratch (nt4 + sp6). We also added a Unix server to our network (to act as proxy and web host).
If I reboot both machines, i'm OK for a while (6 hours or so) then I start to die again! Any comments/suggestions would be great, as I haven't a clue where to go next!

 

[Calgarian]

What licencing option have you gone for??

Per seat burns through licences more slowly than per connection.

 

[Dunalastair]

I'm using server mode licensing (I have used that mode for about 4 years on the previous hardware, and never had a problem) There is no significant increase in the number of workstations over previous 2 years.