Oracle Database Discussions

Hi,
We are having troubles with sessions hanging when downloading spatial data.
If I try to download the same data 20 times, more often than not the session will hang at least once, but work perfectly ok all other time. This occurs on multiple clients, in multiple buildings, and on multiple tables in the database.

There are no errors in the alert.log and i could not find any trace files around the time the session hung.

This all started happening when the server was moved from the local network to a remote secure data centre.
The network guys tell me they don't think it is a network problem.

Does anyone have any suggestions as to how I could try to find the problem?

Thanks
Gunter