I believe this is a known bug with 9.0, and will be repaired with SR3. Meanwhile a patch exists that solves the issue. Please contact customer support (email@example.com) and request Customer patch 9.00.7336.
Thanks all for your help. I did confirm this is an issue with QlikTech Support . Gustav was very helpful in supplying us with a patch to correct this issue. So far the patch looks like it is resolving the problem. This patch will also be incorporated in the new SR3 release scheuduled for Feb 2010.
Releasing the Virtual memory requires a restart of the services.
If you are not restarting the services, then try this and schedule the batchfile to run in the middle of the night.
Create a .bat file and paste this to it. (This will restart all QV services)
REM Stop QVS.
net stop "QlikViewServer"
net stop "QlikView Directory Service Connector"
net start "QlikView Directory Service Connector"
net stop "QlikView Distribution Service"
net start "QlikView Distribution Service"
net stop "Qlikview Management Service"
net start "Qlikview Management Service"
net stop "QlikView Publisher Command Center Service"
net start "QlikView Publisher Command Center Service"
REM Start QVS
net start "QlikViewServer"