Laptop doesn't want to boot from the hard drive but network instead

Hello everyone, I'm having a strange, randomly occuring issue with my laptop.
Firstly, let me describe the boot order set in the BIOS:

HDD1
HDD2
FDD
USB
LAN

Click to expand...

Now, it was recently disassembled to bits, to give it a thorough cleaning and address minor issues like loose hinge and broken battery latch. After that, when I booted it up for the first few times - it worked just fine.

The problem appeared after I hibernated it for a few nights, each time I powered it back up, it wanted to resume windows (didn't show the usual text "press F2 to go into bios" etc.) but instead it entered Intel UNDI, PXE-2.1 build 002 and attempted to boot from the network, but failed (that's okay) with an error message "Check cable connection!" followed by "Exiting Intel PXE ROM." and it repeated the process again - stuck in a loop, spamming the screen with text.

I can press the power button, del, F2, F12 and nothing happens or it'll restart (same with CTRL+ALT+DEL) now, why does it do this? I have no idea. It does do the same thing on fresh boot. The CMOS battery is fine, it keeps time and settings. After restarting a few times in various ways (usually 8!) it will boot properly... I don't have any external devices plugged in except wireless mouse.

I would really love some help with this, it's very annoying and I simply don't know what to do

If the hard drive is not detected the BIOS will just move on to the next item in the list. Your seeing the boot from lan on screen because its the last option and that's where it stops. Double check that your hard drive is securely mounted and any cables are firmly attached. It could also indicate that the drive may be failing. I'd double check all your internal connections first, as you've had it opened up.

Sorry for late reply, it's been a busy week.
I've re-seated the drive, it's securely mounted on it's caddy.
I've disabled network boot in BIOS, instead of that, I now get "Operating System Not Found" message, but I can just CTRL+ALT+DEL (restart) it and it boots fine the second time. MBR issue maybe?

Tried to clear CMOS? I guess for a laptop, remove power cable and battery, wait a few minutes. Press and hold power button, say, 30 seconds. Attach stuff back and retry.

Unfortunately I cannot do that. It would require me to completely disassemble this laptop, and take out the motherboard, which I'd hate to do. I'd much rather re-install the OS and see if that helps any, which I plan on doing after I get new drives.

Thanks for the suggestion though, I'll keep it in mind.

Does your BIOS have a reset option ?
Using that option should reset BIOS without disassembling.
You would have to review/set your boot device settings after the reset.

GokAy said:

Tried to clear CMOS? I guess for a laptop, remove power cable and battery, wait a few minutes. Press and hold power button, say, 30 seconds. Attach stuff back and retry.

Click to expand...

Laptops have a CMOS button cell wired to the motherboard just like desktop PC's do. That won't work.