Error optimizing query - bug

Hello,

I am trying to optimize a simple SQL query, using right click on the SQL statement, ‘Optimize’ -> ‘Auto Optimize SQL’
This is the query:
SELECT COUNT(sub_account) from customers where import_id=111

Sometimes TOAD returns the following errors:

Invalid pointer operation
Unable to establish optimization session.
Access violation at address 01AA6A72 in module ‘ConnPoolLib.dll’. Read of address FFFFFFFC
Access violation at address 01AA35CD in module ‘ConnPoolLib.dll’. Write of address 03DEE388
Access violation at address 01AA3481 in module ‘ConnPoolLib.dll’. Read of address FFFFFFFC

I also got:

Failed to update scenario data file
Error renaming file to:
C:\Documents and Settings\firstname.lastname\Application Data\Quest Software\Toad for Oracle\11.6\SQLTuning\Session103580729~26248709.osd

These errors appear sporadically. Please investigate.
Using the last version of TOAD (11.6) on Windows XP 32-bit, SP3

Thank you,
M.R.

Unable to establish optimization session.

its occuring whenever i autooptmize sql using toad 12c