Since this morning there have been non-stop login attempts against a particular username -all of them failing. There are no active Apex Jobs or batches running and the debug logs are not producing any logs, so we are not sure who or what is responsible.
Login History (showing the last few attempts)
Login Time Source IP Login Type Status Browser Platfor App Cli API Type API Version Login URL Community
12/1/2015 9:22:33 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:33 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:32 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:32 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:31 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:31 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:30 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:30 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
12/1/2015 9:22:30 PM CST Salesforce.com IP Other Apex API Login Rate Exceeded Unknown Unknown N/A N/A SOAP Partner 33.0
This is locking up the user due to maximum login attempts.