NTFS partition went “unknown”

I have Windows XP Pro with two basic NTFS partitions, and a 3rd “HP Recovery” bootable partition. I wanted to use the remaning space (25 GB) for Linux. So I got Linux installed, but when I went back to WinXP, now my 2nd NTFS partition is gone. the MMC-disk managment tool actually shows it there, but with the message “unrecognized partition” and the only option is to delete it. Are there any tricks to recover the status wothout losing the data? I’ll even whip out my old trusty Norton DIskEdit if that’s what it takes.