Task manager is not very good for troubleshooting memory problems, use
Process Explorer instead. Start it and open the File menu and choose "Show Details for all Processes" then add the "Private Bytes" and the "Private Delta Bytes" columns.
The next time you have memory problems click on the Private Bytes column to sort it with the highest value first and take a screen shot then press CTRL+I, select the memory tab and take another screenshot and upload the screenshots here.