strange error in cognos connection

[UseCog]

Hi,

We hav 2 gateways servers load balanced in cognos production environment and recently we have upgraded the Cognos from 8.1 to 8.4. After upgradation we have upgraded Windows SP1 to SP2. Unfortunately after that we cannot be able to access Cognos portal from ONLY SOME OF THE MACHINES at our client side using the cognos url like [gatewayhostname]/cognos8. But the same can be accessed from many other machines using the same credentials. Also cognos can be accessible if we try to connect to individual gateways from these machines(which have issues to connect to cognos connection), like [gateway1_hostname]/cognos8 and [gateway2_hostname]/cognos8.

This issue looks very strange and it would be highly appreciated if some one can give any help to solve this issue.

Thanks,
CG

[ducthcogtechie]

What do you use to load balance, and what is your authentication source?

[UseCog]

Thanks for your reply,

We are using windows 'Network Load Balancing Clusters' for load balancing nad we are using Active Directory for authentication. All users can ping to the common gateway server (using both IP and host name).