Noise from HR21 DVR

We've had our HR21 DVR for over 2 years now and have been happy with it.  About three weeks ago it began occasionally making a growling noise similar to when a hard drive goes bad in a computer.

The noise usually only lasts 5 minutes so I've been ignoring it until last night when access to my recordings became very s - l - o - w.  When the noise stopped, access to my recordings became normal again.

I talked to tech support today and they advised that there was nothing inside my DVR that could make a noise as described and that at 2.5 years old, my DVR was still quite new and not expected to fail.  She suggested that I might have just begun to notice the HR21's internal fan.

She did not offer to replace or repair the unit.

Is tech support correct?  The noise isn't real loud, just annoying.  I could live with it if I had to.

Thanks,

    Mike