During the lunch break (before the 2 hour afternoon session on Genealogy), we powered off the machine and unplugged all the external cables (how many are there ?). Then, unplugging the two memory cards, three PCI cards and the two hard disk ribbon cables on the main-board, we carefully blew any dust out (none was visible since there were no carpeted rooms where we used the computer).
We then reseated all the cables and reconnected everything else. Power on. One single beep. Sounds good. Success !
The morals of the story:
- Don’t think that all your computer woes are virus-related
- If it ain’t broke…