Multiple Identities in Outlook Express 6

Since I set up multiple identities for multiple mailboxes in OE 6.00.2600.0000, I'm having strange difficulties. The worst is this: When changing identities, the login box appears with the WRONG identity (one NOT chosen). If I enter the corresponding password (for the WRONG identity), I get into the RIGHT mailbox (the one chosen); otherwise I get nowhere. In other words, I can get into the chosen mailbox ONLY with the WRONG password. This has been the case since following the instructions of the ISP technician. I don't think anything was done wrong, however. Also, Outlook Express ... locks up seriously at times while changing identities, sometimes even locking up the whole computer (PC clone, Windows 98 OS). What can be done about this?