We saw this all of the time in testing when the JRE was not configured with the extra memory.
We also saw this when the JRE memory was changed, but there was still a JRE running on the machine.
All JREs have to be stopped in order for the new setting to take affect.
So be sure to close all explorer and other web browsers after editing the JRE settings. Or better yet reboot your PC to ensure all JREs are stopped so the new settings will take affect.
You might also see this issue if you try running multiple IDMs. Connecting to the same sensor, or even connecting to multiple sensors. Each IDM instance will need 256 Meg of memory.
I used to see it when I used the same IE window to start different IDMs on the same or another sensor.
Once IDM starts be sure to close the original window where the connection was made. You will see this wording in the window: "Close this window and open a new browser window to continue web browsing" This includes even connecting back to the same sensor to start IDM again. Close that window and open a brand new window if you need to start IDM again.
To do some further debugging you might also consider configuring your JRE to open the console.
Go to Control Panel.
Double Click Java Plug-in
On the Basic Tab click "Show Console"
Click Apply
Now connect to the sensor.
A Java Console window should popup.
Keep an eye out for any errors (like out of memory for example).
You will see some debug messages every now and then, but any errors could give a clue as to what is going wrong.
You can also execute "m" in the Java console to print the current memory statistics.
You will be able to see how much memory the JRE is allocating and how much is free. NOTE: When the percent Free starts getting Low then it will allocate additional memory up until the full 256 MB is allocated.
If the free memory ever drops to 0% with the full 256 MB allocated, then you've come across an issue. Close down the IDM and the browser you started it from. Then open a brand new browser window and connect back to the sensor. Execute "m" in the console window and ensure that the total memory is fairly low when IDM initially begins to open, otherwise another JRE instance may be using up the memory.
If your PC itself is low on memory then it is also possible that there is no memory left on the PC for Java to allocate.
NOTE: If you don't want the console window to always popup you can leave it Hidden by default and instead just Right Click the Java Icon in your System Tray and select Open Console when you want to look at the Java console.
