Phone discharges when plugged in to charge

[luv2brew]

Hope someone can help me with this one!  Every night I plug in my phone  using the supplied charger (turned on) and let it charge while I sleep.  I have found that several times in the past few weeks (notably the last 2 nights running) when I do this, in the morning it is completely discharged and the battery is dead.  Last night I verified that the charging light was on and a solid orange when I went to sleep.  When I got up this morning, no light, no response, until I unplugged, re-plugged, and let it charge.

I saw on some other forums that there was a reference to this problem in older versions of the Incredible 2 software, but it sounds like that was fixed some time ago.  I'm on:

Android 2.3.4

HTC Sense 2.1

And I am not being notified of impending updates, so I assume I have the latest and greatest. Note that this doesn't correlate with any software installs that I can see either.

Any ideas?