My computer won't successfully start up

I don't exactly know where this topic should be posted so I guess I'll post it here.

Even though it's going to be extremely long, I'll explain everything. I don't know a whole lot about computers, but when my old hard drive was corrupted, I bought a Seagate hard drive. I thought I had cloned my old drive to the new one, since everything operated much faster than before. Then 3 days ago, my computer emitted a load buzzing noise and I got the BSoD. I restarted my computer and I was greeted with a login and screen similar to Safe Mode, but it had my background and everything. Whenever I tried accessing CMD or anything else, a popup would appear. I then managed to load up SlimDrivers and update a bunch of drivers (horrible decision). I restarted my computer, and was greeted by the Window 7 loading screen and was shown a screen saying that it was trying to fix my C: Drive, but an error occured, 766f6c756d652e263 3f1. And right after that my computer suddenly restarted and the Advanced Boot Mode options appeared and Last Good Configuration was on the list. I tried loading up in Safe Mode, but it always pauses/freezes at CLASS.PNP.SYS (I placed it on for at least 2 hours and nothing). Last Good Configuration and Normally all lead me into an endless cycle of restarts. When I started up my computer again yesterday, instead of getting the Advanced Boot Mode menu, I got a screen saying that I needed to insert my Boot Disk (not even sure I have that, but I do have the OS disc). And then I restarted my computer again, but this time it said "PXE: MOF: Exiting Intel Boot Agent" and was stuck on it. This only happens when I have my old hard drive and new hard drive plugged in at the same time. It also happens when the new hard drive is plugged on only. However, when I have the old hard drive plugged in only, I get the Advanced Boot Mode menu and the restarts. BIOS shows up occasionally, but I'm not sure if that's going to resolve this issue. Any help?



Old Hard drive + new = Stuck on PXE: MOF: Exiting Intel Boot Agent
New hard drive only = Stuck on PXE: MOF: Exiting Intel Boot Agent
Old hard drive only = I get the Advanced Boot Mode menu, Configuration + Normally sends me into an endless loop of restarts plus the 766... error, and none of the Safe Modes will get past CLASSPNP.SYS



Sorry if this is extremely convoluted, but I really need to find any solutions to fix my computer without losing all of its files, etc.

If this is too convoluted to follow, I will gladly answer in sections.

E: BIOS System Setup thing does work even with the two hard drives plugged in.

Before a repair install, I would recommend trying to fix things like a busted MBR and stuff like that.

What I usually do is boot to a Macrium Rescue disc and click "Fix Window Boot Problems". It will reassign drive letter correctly, fix the MBR and other stuff under the hood.

This has saved me countless times and doing this has solved Windows boot problems just about every time. If not, there are other, less time-sink type things that can be done before doing repair installs and that kind of stuff.

Might be quicker to reinstall Windows with only the new hard drive connected using the below tutorial
Clean Reinstall - Factory OEM Windows 7

Lighter said:

There is a slight problem. My OS doesn't appear in the System Recovery Options. The only option I have is to select Load Drivers.

If your OS isn't listed in the Macrium rescue disc, then you should run a startup repair.

The Marcium method might not work on the computer.

But, Startup Repair does nothing. It will scan for a few minutes, restart, and no change. Right now, I have no clue where my OS/Load Driver is located in my hard drive.