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?