"No mapping between account names and security IDs was done" when importing Scheduled Tasks In Windows 2008?

OK, I have a Windows 2008 Server scheduled task that runs on system startup. This works fine. But I want to move this task to another box (actually, I'm using Amazon and need this to work on other instances launched from this image but that's complexity not relevant to the problem).

So I export the task to XML, and try to import it using schtasks. But when I try to reimport it on the same box (just by changing the name), I get

C:\>schtasks /Create /XML "mytask.xml" /TN "My Task 2"

ERROR: No mapping between account names and security IDs was done.
(17,8):LogonType:

I look, and I notice that in the Principals section it says

 <UserId>IP-0AD68720\Administrator</UserId>

Which will make me sad when I try to move this task to another box. But if I edit that to just say "Administrator", when I import I get this error:

ERROR: Logon failure: unknown user name or bad password.

So I can't even reimport it on the same box, and can clearly see I'll have trouble importing it on another... Any hints? I want to alter the task so I can use it on other boxes to accomplish the same goal.

Thanks...