The error is occurring when CatTools is trying to create the report file to email. Seems you are running out of system resources. Did the reboot fix it?
You may also want to check that the 'Overwrite existing report file' option on the 1st tab of the Activity setup screen has been selected. Without this item checked, you will append data to the existing Port Info master report text file, instead of creating a new one. This should also improve system resource issues.