This error means the BIOS thinks the hard disk is not bootable. So get your Windows 7 DVD and go into Startup repair.
http://pcsupport.about.com/od/toolsofthetrade/ss/windows-7-startup-repair.htm tells more.
I am using window 7 4gb ram laptop. But one day when i boot up it shows this
PXE-E61 : Media Test Failure, check cable
PXE-MOF: Exiting PXE ROM
Then i borrowed Hirens boot from my aunt and i was able to boot it as Mini XP. I see my hardisk is working all the files are in it and perfectly health. Hope you guys can help