SOLVED UEFI Multiboot failure

(Quick replies are MOST welcome, I'm spending my night doing this instead of... anything else....)

Happened to me before, only this time it's REALLY getting annoying.

I have a 3Tb HDD used as a main drive, GPT. So I boot in uefi on a regular basis.

But then... everytime I try to boot from ANYTHING else, for any reason, it doesn't want to boot back to the main. It boots up, says that "windows has not closed correctly", usual two choices of 'Launch startup reprair/start normally.

If I choose normally, it shows the windows logo for half a second, then sends me back to the BIOS, no reboot or anything.

If I choose repair... endless loop the choice screen.

If I boot from the CD, there is nothing to do to make it work. (Last time I succeeded after 3 hours of randomly choosing either startup repair, which worked at the time, and CD repair).

Under diagnosis, error code: 0x490.

Note: I can't even access the drive's startup repair this time. My only option is the cd.

I have tried many things from many differents forums, and yet nothing seems to do it.

Any way of NOT having all that crap?

/e: UEFI and GPT is still a pain in the ***, looking forward it being the standard. There's tons of pages all over the place, each being a different problem...

/e2 found a command that wasnt in the other threads i've read: bootrec /rebuildbcd didn't work.

I don't think gpt will become a standard. WD and Seagate put larger mbr's on their disks after breaking 2TB mark afaik, to allow mbr use again. I'd say move your data out, fresh install, and why not an ssd. Learn to use symlinks/junctions, and you'll even manage to run windows on a 64GB ssd

Fixed.

I installed linux on a 2nd hard drive, and it was conflicting with windows' boot.

Disconnected it, fixed.