Cpu unworkable / underclocked itself

Hey thanks for ur time, heres my problem.

About 2 weeks ago i turnd on my pc and there was this grinding noice, it was from the northbridge fan, the sound of the bairings, like there was alot of dust in there, it was dry or something, it goes away after 2 -5 mins and spins silently (warmed up i sopose as its cold in here)
I got this msg at boot up dispalying the speeds etc of enything except the cpu i think, and it also said CPU has changed or is unworkable, press f1 to boot or del to go into bio and fix. in the bios everything seems correct (not sure wahts the default multipl

I get this everytime i turn my pc on (the fan just the first time i boot up that day) the msg after every time its turned on rst etc, i think teh northbridge has dust cloged in it so i may need to replace it , but it is working, but im unsure whats wrong with the cpu, maby a cmos reset will fix it. it is running at 11-14mhz slower than stock. im just unclear why its started doing this, i havent touched anything lol, could a slight f**k up in the northbridge fan cause the cpu to unclock?

Image from MBM5
http://img139.exs.cx/img139/747/mbm51sv.jpg
this is prity average figures, normal idels at around 47 degrees, highest its reached is 66 where the alarm went NEEEEEE NOOOOR this was when the load was heavy (compiling a hl2dm map) but i put big fan on and the side off, took it down and the alarm stoped, so i dont think its overheating porbs on the cpu.

Spec:

Pentium 4 "Northwood" 3.0GHz (800FSB) (use to display in irc as this)

(CPU) 2-Intel® Pentium® 4 CPU 3.06GHz, 3006MHz, 512KB
now its this
(CPU) 2-Intel® Pentium® 4 CPU 3.00GHz, 2992MHz, 512KB

Abit IC7 max-3 (think bios version 16, never touched it as everything worked after build fine)
Corsair Twinx xms 4000 1gb matched pair
9800 pro 128
1 sata, 1 ata hd
1 cdr, 1 dvd drive
Creative 5.1 live card
and a pikey q-tec 400w psu (last thing to replace when i got cash)

Everything has stock coolers, have all new coolers ready to go on next week.
anyhelp would be ace thanks for ur time.
p.s soz for the crap spelling, i cant spell to save my life.