Insert boot disk" error: how to fix?

Hey, I’ve got an issue with my HP Pavilion dv7 running Windows 7. Every time I power it up, I just get a black screen staring back at me with a "insert boot disk and press any key" message. Since I bought this used, I don't have the original recovery disc that usually comes with these things... also, the left side feels incredibly hot—I'm going to let it cool down before I try anything else.

It looks like one of your Windows files got corrupted, so you're probably going to need to run a repair. If you don't have a recovery partition handy—which happens more often than you'd think—you'll likely need to grab a Windows installation disc and either perform a clean install by formatting the drive or just attempt a system repair.

Regarding that overheating issue... when was the last time you actually cleaned the dust out of it? And where do you usually keep the laptop? If it's sitting on your bed, that could be part of the problem. You might want to pick up a cooling pad; they aren't exactly expensive, and they can make a huge difference.

The laptop powers on, but I can't get any real work done—it just cuts out. I stepped out to the grocery store and when I got back, it had shut itself down and restarted with that error message. It hasn't been opened up or cleaned in ages... I'll have to deal with it today, and I probably need to pick up a new fridge somewhere too. It’s likely just the heat today—I'll mess around with the machine again tomorrow and see where we stand