Faulty Fan Failure Error - HELP!

[Lucjan]

It's a 2003 machine. CPU is not watercooled, it's aircooled, but there's no fan directly connected or directly facing or directly anywhere near the cpu.

All the fans in the machine do run properly when turned on, despite the error message.

It's a compaq P8656V from the S6000T model series, if that helps any. (Since then I've replaced all the ram, the power source, the video card, and added an extra fan)

EDIT - This started happening last night, according to my mother who discovered the issue. (Before I went to work last night it was running just fine.)