Hi,
Sorry to have to ask these questions - you have probably already checked these things.
Have you ensured that you have not specified the database in local.properties or the vmoptions files?
Are you using the Load Test Report Generator?
Have you shut down everything and deleted lisatmp before restarting?
As an aside, an overloaded database is one where the processing capacity is exhausted rather than one that has no space for data. Similar symptoms may be encountered when network latency is the dominant factor in the database transaction time. What are your ping times from the various components (registry, coordinator, simulator, VSE, workstation) to the database? What does the registry log show the db ping time as?