I faced an odd problem with a client today and wanted to document it here in case any of my fellow tech support peers runs into the problem with one of their clients.
Configuration: HP Desktop PC, Internet Explorer, HP SimplePass software by Authentec
Symptoms: Internet Explorer continues to AutoComplete/AutoFill a username password on specific web pages even after AutoComplete has been disabled. In this specific case, the username/password for a given web site was auto-completed and enter was pressed to attempt an Auto Login. Since the username/password pair was incorrect, it resulted in several login errors which quickly activated the lockout of the account.
Solution: After searching for additional web toolbars and Add-Ons that might be trying to store and autofill login information, I happened upon mention of the Authentec TrueSuite plugin listed as an Add-On in Internet Explorer. The disable option was unavailable on this Add-On. Searching the Windows Installed Programs list showed no entry for Authentec products. Looking at the informational dialog for the Authentec plugin revealed that the local file name was, instead, HP SimplePass. Obviously, HP had "white-labelled" the Authentec software for inclusion in their PCs. I located the HP SimplePass program in the Windows Installed Programs list and removed it. After this the AutoComplete/AutoFill behavior disappeared.
Notes: It is very odd that this program was causing this behavior, as the HP SimplePass is supposed to be limited to interaction with fingerprint scanners included in some HP laptop products, while this was a desktop PC running Windows 7. It was also odd that the Authentec AddOn for Internet Explorer could not be disabled or removed from Internet Explorer, but required the removal of the entire HP SimplePass install.
Link: Information on HP SimplePass