When running a query using the "Execute as Script" button from the Editor, the results create Out of Memory, which retains the data in memory.
After running a query the results are dumped into the output tab. Toad needs memory to keep the data in there.
Resolution 1:
Clean out the Output and Grid tabs by closing them or deleting what is in there.
Resolution 2:
Increase the page file size (virtual memory), see link below for more information:
http://support.microsoft.com/kb/308417
Resolution 3:
In Toad perform the following to decrease the number of rows returned:
1. Select View | Toad Options menu option
2. Select Execute/Compile from left
3. Check "Limit results to" check box and enter 20 or decrease existing number in the field
