Just in case I havnt explained myself too well the folder I refer to is My Computer/C drive/Documents & Settings/[UserName]/LocalSettings/ApplicationData/Identities/Hostofletters&numbers/Microsoft/OutlookExpress/ You should then be in your folder store with all the dbx files. Note you will have to "Show all hidden files"as the LocalSettings folder is hidden.
She tried rebooting but still gets a new SENT ITEMS (1).DBX created. I've looked in my registry for both Win98SE and WinME but can't find a pointer, it's well hidden somewhere. It's no real problem, I think she'll have to put up with it.
Incidentally the mail boxes in 98SE and ME are both in C:\WINDOWS\Application Data\Identities\GobbledyGook\Microsoft\Outlook Express, you must be referring to XP.
Here's what happened, she regularly goes to the folder where IN and SENT dbxs are, uses right click, send to, to back up. (following Dad's suggestion to make regular backups)
At some stage she thinks she must have done right click, delete against SENT ITEMS. She noticed it when using OE and it was empty.
So effectively she deleted SENT ITEMS.DBX and OE created SENT ITEMS (1).DBX. She is now backing up the (1) version. I know it's no real problem but I'd like to know where the pointer is stored. It's a mystery.