A customer calls me: He has just returned home from 3 weeks of holidays, and his computer is no longer working. He needs it for work, so I go see him the very next day.
While booting the desktop PC, what looks like a disk error appears before windows can start (ie at the bios level) The PC will sometimes get past this error & windows waits at the startup screen for over 10 minutes before generating an obscure error message.
I suspect there is a problem with the disk caddy system, so I try to connect the disks directly to the IDE cable.
The problem persists even after a direct connet to the HDD… But things seem a little better… Windows sometimes starts normally but while doing a disk check, the system suddenly reboots
I start suspecting a few “difficult to diagnose” problems (motherboard, power supply).
While looking inside the case, I notice that the CPU fan blows air directly onto one of the memory sticks… the memory & the socket its plugged into has a layer of dust, so I take out the memory, give the memory & socket a clean, then put the memory back, restart the computer & the system POST gives a continuous beeeep.
Aha! now here is a more solid problem! I take out the suspect memory & the system boots just fine. I take out the good memory & put the suspect memory in its original socket: lots of beeeeping again. I place the suspect memory into a different socket: It works perfectly.
So the memory is fine, but the socket is suspect (either faulty, or its not possible to remove all the dust). Either way, the customer is happy to leave the running system as is. He’s glad to be able to get back to work (having lost a mornings work).