You are right I'm seeing heartbeat problems just before un-registration.
#2014/Apr/26 18:17:32 MOBILITY Hot Desk : 2261 logged out from 1981 by system during registration
2014/Apr/26 18:17:25 MOBILITY Hot Desk : 2402 logged out from 8046 by system during registration
2014/Apr/26 18:17:21 MOBILITY Hot Desk : 2448 logged out from 8171 by system during registration
2014/Apr/26 18:17:00 MOBILITY Hot Desk : 2334 logged out from 8075 by system during registration
2014/Apr/26 18:16:44 MOBILITY Hot Desk : 2285 logged out from 8131 by system during registration
2014/Apr/26 18:16:28 MOBILITY Hot Desk : 2236 logged out from 1954 by system during registration
2014/Apr/26 18:13:17 Heartbeat Server ICP has lost contact with (10.80.10.253 (08-00-0F-7A-7B-90)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:13:16 Heartbeat Server ICP has lost contact with (10.80.10.235 (08-00-0F-7B-77-32)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:13:15 Heartbeat Server ICP has lost contact with (10.80.10.228 (08-00-0F-7B-77-09)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:11:22 MOBILITY Hot Desk : Logged out from 1913 - Associated hot desk user was 1015
2014/Apr/26 18:11:22 MOBILITY Hot Desk : Logout of 1015 from 1913 initiated
2014/Apr/26 18:04:12 Heartbeat Server ICP has lost contact with (10.80.10.230 (08-00-0F-7B-6F-5A)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:04:01 Heartbeat Server ICP has lost contact with (10.80.10.144 (08-00-0F-7B-73-A3)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:04:00 Heartbeat Server ICP has lost contact with (10.80.10.171 (08-00-0F-7B-7E-0C)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:04:00 Heartbeat Server ICP has lost contact with (10.80.10.109 (08-00-0F-7B-7D-BA)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:03:59 Heartbeat Server ICP has lost contact with (10.80.10.52 (08-00-0F-7B-77-41)), network driver cluster pool free: 3014 and low water mark: 2575
2014/Apr/26 18:03:58 Heartbeat Server ICP has lost contact with (10.80.10.35 (08-00-0F-7B-7D-BF)), network driver cluster pool free: 3014 and low water mark: 2575