I'd recommend you don't use a vacuum cleaner to clean it out because they're almost as bad as cats as far as static electricity and the conductance thereof is concerned, which is why compressed air exists. It's impossible to clean out your PS3 even nearly enough unless you take it apart, though, because dust will be packed into the heat stack with nowhere to go. In fact vacuuming the vents does absolutely nothing and is just a placebo because if you have enough dust to be clogging the vents, then the heat stack will definitely be clogged also, the vacuum won't shift that and there's no point having nice, clear vents that do nothing because the fan inside the PS3 can't draw air in or out through them.
Anyway, this doesn't sound to me like a heat issue either. Listen to the hard drive for any clicks or loud noises, which is what seek errors sound like, and if you do hear any then your hard drive is dead or dying. If rebuilding the database doesn't work, try taking the hard drive out, put it in a zip lock bag and put it in the freezer (yes, really) for about, I don't know, an hour, put it back in the PS3 (sans freezer bag) and try to rebuild the database again. If that doesn't work, either buy a new hard drive or a new PS3. If it does, back up what you can and buy a new hard drive. No matter what happens I do recommend you open your PS3 up (if that's something you're comfortable doing) and blast the dust out with compressed air. Not only is it a massively satisfying thing to do but it also helps the PS3 out a lot. I apologise if this post is redundant, off-topic or in any other way inappropriate, I'm posting from my phone and I can't remember exactly what this thread is about anymore, but hopefully this is of some help in some way to someone.
Mine was a YLOD. I still have it. 
