NW 6.5 SP3
BM 3.8 SP3
VPN Client 3.8.9

After working perfect for some days VPN stops working. STOPVPN hangs the
server and i can only reboot to bring VPN service up again.
The Clients get the following error message:

"An error was reported by the IKE application
Either %s is an invalid VPN server address or the IKE is not loaded on
the VPN server. For more details please look at IKE log."

IKE LOG says:

IKE Debug Log start time :11.4.2005 16:06:53
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/C2S001.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/C2S002.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/SRV001.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/SRV002.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/C2S001.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/C2S002.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/SRV001.DER
11.4.2005 16:06:53 Read trusted root cert file SYS:/ETC/IKE/ROOTCERT/SRV002.DER
11.4.2005 16:08:14 ***Receive Main Mode message from 10.11.100.108
11.4.2005 16:08:14
I-COOKIE=BF843D904D20E113,R-COOKIE=0000000000000000,MsgID=0,1stPL=SA-PAYLOAD,state=1987986184
11.4.2005 16:08:14 Start IKE-SA 6AA59000 -
Responder,src=192.168.10.10,dst=10.11.100.108,TotS A=1
11.4.2005 16:08:14 IKE SA NEGOTIATION: Peer lifetime = 28800 My lifetime=28800
11.4.2005 16:08:14 sending notify message type: 28 to 10.11.100.108
11.4.2005 16:08:14 ***Send Unacknowledge Informational message to 10.11.100.108
11.4.2005 16:08:14
I-COOKIE=BF843D904D20E113,R-COOKIE=A326F47AAFFFE772,MsgID=84877E53,1stPL=NOTIF Y-PAYLOAD,state=1987986348
11.4.2005 16:08:14 Error :Server certificate not available , probably error
reading certificate
11.4.2005 16:08:14 Processed SA-PAYLOAD unsuccessful - No usage certificate
available for signature authentication, dst=10.11.100.108.
11.4.2005 16:08:14 Error processing the first MM packet - No usage
certificate available for signature authentication
11.4.2005 16:08:18 IKE-SA 6AA59000 is
Deleted,I-COOKIE=BF843D90,R-COOKIE=A326F47A,dst=10.11.100.108
11.4.2005 16:08:18 State:0 Cond:4 TimerEvent:1
11.4.2005 16:08:18 lifetime :0 sec Rekey Time :0 sec
11.4.2005 16:08:18 Created at :0 sec Remaining life time :-463010 sec
Current time 463010
11.4.2005 16:08:18 The client 10.11.100.108 removed from vpninf

11.4.2005 16:08:18 ***Receive Main Mode message from 10.11.100.108


Thanks in advanced!
Gerhard