Recently I have been getting this message when I boot my computer.

I only have Windows XP loaded.

Surely Boot.ini is used when there is a choice of OS a boot time??

I have checked and there is no file on the c: drive.

What should I do?

^repair the installation? (do you have original os cd?)

You probably can't see it as it has the attributes hidden, system, read only. Does your system boot at all or are you using a 2nd boot device to look for the file? The file should look like the below if not a dual boot system. You can use a dos prompt to look for hidden files using the "dir" command. If it really is not there then use notepad and put the below information in it and copy it to the c:\ root directory (this is assuming you are using a 2nd boot device to do this. Then change the attributes of the file to hidden, system, read only.

[boot loader]

timeout=30

default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS

[operating systems]

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect

Also the below information towards the bottom of the source page:

Windows XP Professional also has a command line utility for manipulating boot.ini called bootcfg.exe. (It may or may not be in a Home Edition installation.) It is described in this Microsoft reference. It can be used in the Recovery Console to repair a damaged boot.ini file or in a command window to edit entries to the file. There are a number of different switches and these are illustrated in the output to a command window shown below.

Source:

Dumb observation

I've had this issue when I've left a USB drive plugged in, the PC is attempting to boot from said (previously a system drive) drive.