Let me help you out in driving away this problem. This trouble may happen when the boot.ini file is missing or corrupted or damaged. Troubleshooting this problem is quite easy and for that you need the operating system disk. If you have it, then it's cool. Let's start it right now and fix the problem.
Let me walk you though some simple steps, kindly follow that.
First you need to change the Boot priority of your computer, in order to boot from CD\DVD or Hard Disk. Normally by Default that will be HDD (Hard Disk). Now to change the Boot Priority you need to go to BIOS page.
First restart your Computer. At the time when it starts, start tapping F2 or Delete key or F8 which ever key assigned by your computer manufacturer to enter into BIOS.
Once when you are on BIOS, just use the keypad arrows to navigate. You may see a tab named as Boot. Go there and you may find the Boot priority set, just below the Boot tab.
Now in that page just select the Boot priority 1 to CD\DVD Drive and and then hit F10 to save and exit.
Now the system reboots. Before that, you should have inserted the OS disk on to the disk drive, so that on restart it may check for disk to boot form.
Once when it is restarted and the disk is in. It may ask you to press any key to boot from Disk. At that time tap enter.
So that the Computer starts to boot from the OS CD.
When you receive a welcome message displayed, Press R, to start the Recovery console that may take you to an command prompt. Where it also asks for the Administrator username and the password. After you key in the Administrator username and the password, press enter.
Now on the command prompt screen type in as, bootcfg/list which may list all the boot.ini files.
Then type in as bootcfg/rebuild. When you do this, it searches' the entire file system and it rebuilds the boot.ini, with the suitable files that may be missing or corrupted. So this is one method of solving the problem .
The another method is also the same as this one but you need to run a repair installation, which may checkout for the affected areas and then it replaces it with actual one..
Hope this will finally solve the problem.