Thanks, Pokeratis, for the thought, but as Celik notes, I not only tried cleaning the GPU and CPU heat sinks, I *did* clean them. I'm trying something else now, that is relevant to the time period in which I noticed the problem. I am determined that I *will* discover the cause of this and fix it. It's sort of like figuring out how to properly attack one of the Marauder NPC's. :)
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Remembering Tyneetryk
Phaedreas Tears - 15 years old and first(*) of true neutral guilds in Atys.
(*) This statement is contested, but we are certainly the longest lasting.
<clowns | me & you | jokers>