Never mind. Solved the problem by downloading new Foxfire browser. Works like a charm but I still can't figure out why it stopped inserting addresses.
A puzzle. After importing a bunch of addresses to Yahoo mail, Yahoo suddenly stopped allowing me to insert addresses from the address book into composed messages. I click ok and nothing happens. Am using Mozilla and have windows ME. The puzzle: when I switch to IE I can insert the addresses. Also, when I access my Yahoo mail on another computer also with widows ME and using Mozilla I can insert the addresses. Have deleted cookies, temps, references to Yahoo and anything else I could think of and the problem remains. Any ideas?