If it is ISASS, it's not a valid Widows process. If it is a typo and is LSASS, then it's probably legit if properly located. The error message you describe could be due to an error in the process that authentictes user logins. I would try to replace the original SAM file and see what happens. If you just deleted it, you might have an issue.

I would also recommend that you do not use Linux to write to an NTFS partition. The process is risky and I personally would not use it if I wanted to keep the dtata on the partition. I know it is claimed that 5.0.1 can write to NTFS, but that does not mean it is flawless and miught not corrupt your information.

There are many tools you can use to write/replace the SAM files. One good tool for accessing and writing to an NTFS partition is BartPE. You might look here: http://home.eunet.no/~pnordahl/ntpasswd/bootdisk.html Someone recently pointed me there, but I have not used it and cannot therefore recommend it.

I would also search around on the Micro$oft site to see if there might be some good advice on this. They have tons of info if you would care to look for it.