Unable to boot after install error extracting files from "Essentials.pkg"

[Bonesetter]

I decided to try and upgrade my perfectly running Mavericks install to Yosemite and I ran into a ton of problems and now am confused and not sure what to do. Here's the sequence of events:

-Attempted to upgrade my Mavericks to Yosemite using the guide
-Installation hung at 19min remaining and I got the infamous error of unable to extract files from Essentials.pkg and after a few hours of searching the forums and web I decided to try and restore my Mavericks
-My Mavericks install would no longer boot and upon trying to boot from my CCC cloned drive, I got a kp
-Booted from my old Mavericks USB stick and attempted to restore from my Time Machine backup. Upon trying to boot my restored drive it froze at the apple logo.
-In the process of trying to boot different drives, I somehow booted my Win7 drive on accident, which worked fine at the time.
-Tried booting my CCC clone drive again using the USB stick as the boot loader and it booted up just fine this time. Wasn't sure if I should try installing Mavericks over the failed Yosemite install to keep my personal stuff or just erase my Mavericks HD and clone my backup clone of Mavericks using CCC.
-While contemplating what to do, I instead re-installed Multibeast on my Mavericks drive because the drive appeared to be fine when looking at file structure and checking it out with disk utility. Lo and behold, it booted by using the USB stick.
-I can now boot either my cloned backup of Mavericks or my original Mavericks drive from the USB stick
-I noticed that when I'm in either my Mavericks install or my CCC Clone of Mavericks, my Win7 drives no longer show up on my desktop or in disk utility. However, whenever I turn on my PC, it tries to boot Win7 and I get an error screen asking me to start normally or try to repair the drive. Neither works and it gives me a quick blue screen and my PC restarts.

So...I have no idea how to get my pc to boot Mavericks again by default as it still is the first in order in the BIOS and I've reinstalled multibeast several times. Why would my windows not boot now from the USB stick boot loader? (it actually shows up here as the 2 separate partitions like normal, but gives me the same error if I try to boot as it does if I just turn the PC on and let it run.)

Sorry for the lengthy post, just hoping it makes sense and someone can give me a hand. Thanks in advance!

 

[Bonesetter]

I managed to get my Mavericks drive booting and running again after doing the boot0=error fix and using the latest multibeast for Mavericks. Only change now is when I start up my PC it doesn't auto boot Mavericks, it gives me my list of my cloned drive, Win7 and System Reserved drives, and my Mavericks drive without having to hit a key to choose.

Now, I can't for the life of me figure out why my Win7 drive won't boot. I've tried unplugging all my drives except my Win7 drive and it keeps crashing on startup and then attempts to repair on the next startup and doesn't actually repair or find any problems. What's even more strange to me is, I also have a WinXP drive that I used to use all by itself because I was never able to get it to show up in the list of drives, but this drive will no longer boot by itself either. Any ideas what would have changed by just doing a botched Yosemite install that would make it so none of my windows drives boot?!?? (Or better yet, how can I fix it?) Thanks!