Reboot and select proper boot device!!

GOOD day..

last week i opened my CPU and cleaned it..
then when i was finished i start it up..
it booted with no problem at all..
then after 5mins, it suddenly switched off..
i turned it on again, but still it switched off..
when i start it up again, i saw a temperature error..
then i turned it off for about 10mins..
then when i turned it on again, it didn't restart anymore...

yesterday, i opened my pc again and cleaned it..
when i was finished, i switched it on..
it did switched off again after i turned it on, but only once..

today it did switch off for 4 times, then when i switched it on..
the error appeared "Reboot and select proper boot device".

i switched it on and off but still it the error appears..
i didn't remove a wire or did anything.. just cleaned..

pls help me... BEFORE that error appears too, i just open the CPU,
and make sure the cable in the HD is connected, then it boots fine..

in BIOS the 1st boot is HD..
when i press F8 only CDD drive appears..

what seems to be the problem? help me pls..

 

Your CPU may be overheating. Did you put some thermal paste between the CPU and the heat sink? Maybe that's what you cleaned out. You need thermal paste in there to help conduct heat produced by the CPU to the heat sink, which then conducts it away.
If the CPU overheats, it should switch off to protect itself. That may be what's happening.

 

my problem is, cpu doesnt detect my HD.. only the CD drive...
:cry:cry:cry:cry

 

I'm not able to look at this right now, but in case someone else is having a look, perhaps you could add a bit more information.
Firstly, when you say CPU, do you actually mean the computer case? The CPU is a small thing about the size of a squashed matchbox. On reading your posts again, I think you mean the case - the box that holds all the bits.
What exactly happens when you try to start it normally? What do you hear and what do you see?
You seem to have tried to start it in Safe Mode. Yes? What do you hear and see then?
What operating system are you running (eg, Windows XP SP2)?
You seem to be saying that you have made sure the hard drive cable is connected. Check the other end of this cable as well and make sure that is properly connected too. Please touch the metal case with your fingers before reaching inside the case - to remove static electricity (and make sure it's off and disconnected).
Make sure all other connections are good too, including the RAM.

 

PROBLEM SOLVED...

i removed the battery and reset the BIOS..
now it's ok.. i still dont know how to resolve the SWITCH OFF issue..
the overheating.. i dont know what that thermal paste is..

 

Don't worry about the thermal paste - I thought you had removed the CPU (the little thing inside the computer) and cleaned it. If you did that, you would need thermal paste.

So now you can boot, but your computer keeps switching off. Is that right?

It sounds like you have overheating issues, and your computer is switching off to avoid damage. It may be that one of your fans has stopped running, or it is not running well. Have a look inside the computer while it's running (be careful) and see if you can see any problem with the fans.

Do you have Everest on your computer? That tells you what your temperatures are. You can get it free from here:
http://www.majorgeeks.com/EVEREST_Free_Edition_d4181.html

 

Yes it shutdowns, i dont know why.. it never happened b4..
just after i cleaned the dust..
i didnt touch anything or removed anything..
just brushed it w/ paint brush.. :-D

Here are the temperatures:
Motherboard = 25°C
GPU = 67°C
HD = 47°C

Is it too hot? all fans are working..

 

Assuming you mean "CPU", this could be your problem. This is fairly high, and you may have a setting in your BIOS that shuts down the computer at about this temperature. Mine has three shut-down setting options - 60, 65 and 70C.
If this is the problem, either your CPU fan is not working properly, or you are overworking the computer. Probably a fan issue would be my guess.
You could try cleaning the fan, or else replace it (or the whole heat sink), if it looks like a fan problem.

 

GPU = Graphics Prossesing Unit..

not CPU.. it goes around 68°C when im playing games like Call of Duty...
my CPU is only 26°C...

 

Sorry - forgot about GPU.
Found this:
Stock cooling on a card should have it operating (under load in 3-D) in the 70s range, 80s are tolerable, 90s are hot, 100s - your card is on death row
Other comments are similar. Sounds like you're ok here.
Is it possible you loosened a connection while brushing out your computer?One of the connections might be just hanging on, but dropping out every now and then. Make sure they're all good. Touch fingers on metal case before going inside, to remove any static electricity.Just occurred to me - I have seen computers switch off because the power cord doesn't connect very well into the computer. Make sure it's well pushed in and connecting well (also at the wall plug end). Maybe try another cord as well. (Do you have a cat that walks by 3 or 4 times a day? :-D)