Hello,
Please let us know the following:
1.  Which version of Hal that you are using (4.5, 5, free version, paid version, etc.)
2.  Which brain you are using (default brain, Enhanced Brain, XTF Brain, a brain modified by you, etc.)
3.  How long you chat before this occurs (and any other "activity" information that would help)
4.  How much RAM your computer has
I have heard of this error message but I have never been able to reproduce it in any of my testing on the default brain or the Enhanced Brain.  I definitely want to learn all the details of exactly when, where, and how it is occurring.
Sincerely,
Don