Hi. I have very little knowledge of computers,so hope you could help.Just got a 2nd hand pc, Toshiba,Pentium 3, 800mhz. Its got windows 98 installed. When I started the pc it said "cmos checksum error defaults loaded" press F1 to continue. if pressed it goes to menu. "warning:windows has detected a registry/configuration error. choose,command prompt only and run SCANREG.
The following file is missing/corrupt. C:windows\HIMEM.SYS
C:\> (apparantly I should boot it with dos,is that right, and how do I do it?) thanks

The "CMOS checksum error - defaults loaded" means that the BIOS (the underlying system that works out what's inside the PC even before Windows starts loading) has got a bit confused.

1. Have you changed any of the internal hardware when you got the PC?
2. Was the PC known to be working when you got it?
These are both important questions to answer!

My first suggestion would be to switch on the PC and go straight into the BIOS before it loads Windows. Then get it to auto-detect the hard disks (I have a full explanation of "how to find missing drives" in the Member's PC Help Articles section of the forum). If it thinks that it can't find Himem.sys, it might be that the hard disk parameters in the BIOS aren't right and it's not reading the hard disk properly.

If auto-detecting the hard disks doesn't seem to help, restart the PC, go back into the BIOS and select the Load Fail-Safe Defaults option (might be called something similar like Load Factory Defaults) so that the BIOS switches to its most standard settings. The Save & Exit (or Exit Saving Changes) and the PC will restart and will try to load Windows again.

Let us know whether that helps - if not, we'll think of something else, which will probably involve booting from a Windows 98 boot disk

hi.no I did not change anything,but are not sure if the pc worked before.ok I did what you suggested.first the auto detect hdd and it said none.I restarted pc and then it said boot of atapi cd rom:not found.......e61; media test failure. boot disk failure. insert disk and press enter. then I tried your 2nd option,load fail-safe defaults. it did say success, but still says dont detect boot of atapi cd-rom,insert system disk and press enter.( I can ad that the cd-rom is working,I mean it does close/open)do you think there is no hdd at all?thanks

Hmm, OK, I was kind of expecting that - there seems to be a problem with the hard disk. You'll need to open the case up.

Disconnect the PC from the mains.
If possible, take the base unit to an area of the house that isn't carpeted (to try and avoid static electricity).
Remove the lid or right-hand side (viewed from the back) of the system case.
Towards the front of the case, you should see the CD-ROM drive at the top, the floppy drive in the middle and the hard disk at the bottom.

Unscrew and remove the drive and note the settings for that drive for Cylinders, Heads and Sectors (CHS). It will be probably be shown in a format like 16383/16/63.

Make sure the the jumper (very small plastic plug that sits over a couple of the small pin terminals) on the back set the Master position. There is normally a label on the drive that shows the jumper pin settings.

Refit the drive.

Make sure the grey IDE cable is securely connected to the back of the drive. Push your finger along the connector to ensure it's firmly seated across the whole connector.

Make sure the power cable is firmly plugged in - it should feel pretty tight.

Refit the system case. Plug the mains power, keyboard, etc back in.

Switch on and go into the BIOS. Go to the Auto-detect hard disk option.

If it still says 'None', then go into the screen that lists the drives, move across to the 'Type' field in the 'Primary Master' row and set this to 'User' or whatever similar option you have where you can type in the Cylinders, Heads and Sectors. Type in the CHS settings that you noted down earlier. The 'Size' field should now display the correct size of the hard disk. If it doesn't, there might be a 'Mode' or 'Block' option in the last column on the right, which you can probably set to 'Auto'.

Exit the BIOS, saving the changes.

The PC will reboot and will try to load Windows. Does it work now? If it doesn't, you've probably got a faulty hard disk. We might be able to still try something else though, so let us know (you'll need to tell us if you couldn't follow any part of the above instructions because you didn't have the same options, etc).

Hope that helps