This site will look much better in a browser that supports web standards, but it is accessible to any browser or Internet device.
Passwords are saved in one of two places - in <username>.pwl
or in a cookie stored on the system. For a web page based
password request, you need to find the cookie for the site
in question and delete it.
For password prompt from IE, go to tools, internet options, content, autocomplete and turn on the option to remember passwords.
Deleting the DWORD AskUser in the right hand pane of REGEDIT may help if all else fails.
AutoComplete, User Names and Passwords on Forms
Since your computer freezes when you try to delete
passwords via tools, internet options, content, autocomplete
I suspect the relevant reg.key is damaged.
Using regedit, back up your registry. Export the following reg key and then delete it (just the key, not the whole folder).