System Restore will not affect the new password. Also System Restore can be undone unless you do it in safemode.
You don't say what browser you are using but if it's Internet Explorer try using Firefox as a test or try How to Reset or Restore Advanced Settings in Internet Explorer 7 The same steps work in Internet Explorer 8. Reset will rid you of any toolbars.
I've seen add-ons like toolbars slow IE.
malware is viruses, trojans, rootkits, adware, spyware etc.