It's probably the AutoComplete function, John. I found this, which may be useful:
How To Adjust AutoComplete Settings:You can configure AutoComplete to save and suggest only the information you want. You can choose whether to use AutoComplete for Web addresses, forms, and passwords, or not use it all. You can also clear the history for any of these:
1. In Internet Explorer, on the Tools menu, click Internet Options.
2. Click the Content tab.
3. Under Personal information, click AutoComplete.
4. Select the check boxes for the AutoComplete options you want to use.
How To Delete AutoComplete Entries From The Address Bar List:The AutoComplete feature saves previous entries you've made for Web addresses, forms, and passwords. To delete entries from the Address bar, you must clear your History folder. You cannot clear individual entries from the list of saved entries.
1. On the Tools menu in Internet Explorer, click Internet Options.
2. Click the General tab.
3. Under History, click Clear History.
How To Turn Off AutoComplete:To turn off the AutoComplete feature you will have to go into another section as the option is not with the AutoComplete Settings.
1. On the Tools menu in Internet Explorer, click Internet Options.
2. Click the Advanced tab.
3. Scroll down and look under Browsing, click Use inline AutoComplete and remove the tick.
AutoComplete should now no longer work.
http://www.updatexp.com/autocomplete-ie6.html