Sounds like you may need to increase your Java Memory that TheBrain is utilizing.
It is possible to increase TheBrain's memory allocation by editing the vmoptions file.
By default, TheBrain uses a maximum of 192 MB. This is usually enough but for some operations there may be an issue with running out of heap space.
The example below raises the max to 320 MB, but the number can be higher if needed.
1. Close TheBrain.
2. Create a text file and put the following content into it:
Make sure there is a linefeed (Enter) at the of the text. Save this file and name it TheBrain.vmoptions in TheBrain program folder: (Program Files > TheBrain) or (Program Files (x86) > TheBrain).
3. Restart TheBrain.