Start up failure

[marmotte]

I´m a complete ignoramus about pcs so need some really basic help...
I have an Evesham pc running on an athlon processor and using XP. Happy with it and all was running well until...I downloaded Norton antivirus 2005 and all continued to be well. Turned off pc and the following morning pressed the power button. PC starts up - witness aircraft noise taking off from the fan - but nothing appears on the screen except "power saving" and no beeps or anything else is heard...
Is this as bad as I think? CPU/motherboard failure? What can I do? Is it connected to anti virus?

 

[RealBlackStuff]

Unlucky coincidence I would say.
Open your PC, and try if the fan on the CPU can still rotate. Next try the fans (if there) on the motherboard (northbridge), graphics card, rear fans, powersupply fans.
Use something like a toothpick to make them turn.
All this of course with your PC disconnected from power!
Maybe you find the squeeky one, if so replace.
If not, leave the PC open, connect the power again. Look at the CPU-fan when you try to switch on. Prepare to pull the powerplug if that jet takes off again!
A replacement fan should not be too expensive.