Cannot enter setup

A little more detail of the problem you are experiencing would be helpful to those responding.  Also including your model number would be a start.

 

I am assuming that you can't access the BIOS Setup due to a hardware glitch.  As for the Checkpoint error there is no clear cut answer in resolving it.  Do the diagnostic light codes on the system give an error code which could help pin point the problem?   Depending on the age of the machine a failed motherboard battery can cause a variety of boot up problems.  If the machine is more than a couple of years old or has been sitting unplugged for a while then consider replacing the battery.  For a $3 investment in a new battery it is a cheap item to rule out as the cause of the problems.  Otherwise try these trouble-shooting steps.......

 

Try clearing the NVRAM (CMOS) to see if it resolves the boot problem.  Possibly the information stored in the NVRAM (CMOS) became corrupted which is not uncommon.  Normally you would clear the NVRAM (CMOS) by entering the BIOS Setup, but it would appear that you can not do so.  The alternative would be to remove the battery from the motherboard to clear the NVRAM. (Good time to replace the battery)  With the machine unplugged from the wall remove the battery from the motherboard.  Then with the machine still unplugged press the On button for several seconds to dissipate any remaining electrical charge on the motherboard.  Then re-install the battery, plug the machine back into the wall and see if it will boot normally.

If the machine still fails to boot then strip the motherboard down to the bare minimum.  By bare minimum I mean remove all expansion cards, disconnect all drives and leave just the processor, memory and graphics card in the machine after reseating them.  If the computer boots this way then start connecting each device one at a time until the no boot scenario returns.  This would then indicate which device has failed and is causing the problem.  Also try booting the system without the keyboard, mouse or any other device plugged into the rear of the system.  If you have more than one memory module installed then try booting with only one and then swap them around and try again. If you only have one memory module then try booting without any memory modules installed.  If this procedure doesn't resolve the problem then you maybe looking at a situation where the motherboard has failed.

Awafaie, unfortunately there is no easy solution with the error message you are receiving.  The first thing to do is check the system's diagnostic lights to see if they are indicating an error code which can help pin point the problem.  If they don't then try these trouble-shooting steps....

 

Try clearing the NVRAM (CMOS) to see if it resolves the boot problem.  Possibly the information stored in the NVRAM (CMOS) became corrupted which is not uncommon.  Normally you would clear the NVRAM (CMOS) by entering the BIOS Setup, but it would appear that you can not do so.  The alternative would be to remove the battery from the motherboard to clear the NVRAM.  With the machine unplugged from the wall remove the battery from the motherboard.  Then with the machine still unplugged press the On button for several seconds to dissipate any remaining electrical charge on the motherboard.  Then re-install the battery, plug the machine back into the wall and see if it will boot normally. Depending on the age of the system you might try installing a new battery when clearing the NVRAM.  A failed battery can cause a variety of boot up problems.  A new 3-Volt, CR2032, coin cell battery can be purchased for around $3 (US) and is available at any Radio Shack, computer stores and most discount stores.

If the machine still fails to boot then strip the motherboard down to the bare minimum.  By bare minimum I mean remove all expansion cards, disconnect all drives and leave just the processor, memory and graphics card in the machine after reseating them.  If the computer boots this way then start connecting each device one at a time until the boot up problem returns.  This would then indicate which device has failed and is causing the problem.  Also try booting the system without the keyboard, mouse or any other device plugged into the rear of the system.  If you have more than one memory module installed then try booting with only one and then swap them around and try again. If you only have one memory module then try booting without any memory modules installed. Also try swapping the graphics card for another one.  If this procedure doesn't resolve the problem then you maybe looking at a situation where the motherboard has failed.

system have failed at checkpoint [PnP3]

my computer give me this error what shall i do

 

I Done all you told me & it worked fine for a week then this morning it indicated a problem at Checkpoint [Ismi]!

Awafaie, once again the error message isn't giving a clear cut path to the problem. I am assuming that the diagnostic lights are of no help either. The only thing I can suggest is run the system for a while with the minimum of hardware installed and see if any error messages return.  If it does then there is a problem with one of the hardware items that is left.   You might also post your problem over in the Dimension - General Hardware forum to see what other suggestions you received.