HD's running hot?

Recently I had to move to a new place, and due to extreme space conflicts, my comp must now reside in a not-very-well-ventilated corner.  I usually keep my system running 24/7, and a few days in, it began running erratically, restarting itself.  Upon opening the case, I found the hard drives to be searing hot to the touch.  Now, I'm not the most experienced here, but I've had to open my case up for various reasons over time, and can never remember the HD's being this hot.  I immediately shut down, unplugged, and moved the comp out to a better ventilated spot to cool down.  Unfortunately, it needs to go back to that stuffy corner if I want to be using it again due to my apartment's setup.  Is the ventilation the problem?  How can I alleviate the problem if so--do I need more fans perhaps (let us assume that the comp NEEDS to be in that corner and skip the "try moving it" suggestions)?  I'm sure flaming is inevitable, but I'm not all that experienced yet.  I do know that I've been running this system in exactly this configuration for at least a year now with few problems, so I'm guessing it's the airflow in that corner?

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Using that program proposes a bit of a problem.  I believe that running it while the desk fan blows through the case would give incorrect values, as I'm pretty sure the fan is the only thing keeping the hard drives cool as is.  And I really don't want to remove said fan, even for the test, as the hard drives heat up to frightening temperatures quickly and I don't want to risk a disk failure.

Does anyone have any idea, once again, how this might have happened in the first place?  Everything appears to be the same as it was for the last 2 years that I've had this system.  It only has space for one fan, but I've verified it to be working.  I need a permanent solution, basically--this desk fan shit is not going to cut it in the long run and it's wasting electricity running said fan 24/7.