Something was broken. Example at http://www.pchelpforum.com/hard-drives/92949-startup-repair-hard-disk-not-found-2.html
Unless there are more details I suggest you save your files first then reinstall the OS.
I've seen many different discussions about this but they don't have the same problem I have.
put in the recovery disk but this is what it says
Problem Event Name:StartupRepairOffline
Problem Signature 01: 6.1.7600.16385 Problem Signature 02: 6.1.7600.16385 Problem Signature 03: unknown
Problem Signature 04: -1
Problem Signature 05: ExternalMedia Problem Signature 06: 1 Problem Signature 07: NoOsInstalled
OS Version: 6.1.7600.2.0.0.256.1
Locale ID: 1033