I am running an ECS 6100 mobo with one SATA WD Raptor 150 gb as primary, one Seagate 7200.7 IDE 160 GB(?) as storage and a Sony optical DVD burner. The 7200.7 stopped working (still spins up, but doesn't show up in file explorer, hardware manager or the BIOS), so I removed it, and now I am getting an error message that the OS cannot load.
I booted with the Windows 7 dvd and was able to see the file directories on the Raptor, but that is as far as I can get. I am pretty sure I just need to configure the BIOS properly or possibly move the slave/master/cable select jumper on the optical drive, I just can't figure out where they should be.
My guess is you have run into the downside of a Win 7 safety feature. If you had both drives in your machine when Win 7 was first installed on the SATA unit, it also placed some backup copies of its key files on the IDE unit. The idea is that, at some time in the future when the system files on the SATA unit develop errors, Win 7 will automatically go to the second drive and fetch the backups to restore the corrupt files, then boot. All this saves you a big headache in that circumstance.
However, once this is set up, Win 7 checks for the availability of those backup files on the second drive every time it boots, and will NOT boot if t can't find them. Since your second drive failed and was removed, that is what is happening. I understand that you can fix this problem by doing something like a "Repair Install". but please check for the detail on this - it might be called something else. Basically you have to use your Win 7 Install CD as if you were doing an Install process on your boot drive (SATA), BUT you do NOT do a normal full Install. There is another option you choose which checks all the files on your boot drive and fixes any problems for you.