memory allocation failed

A friend called me saying that her children had poured sprite on her keyboard, as a result the key board was not working. I promised to get her another key board from a friend who had an old one. The next day a got an old keyboard anf took it with me to install it for the friend whose keyboard wan not working.After installing it, and starting the computer,the computer could not loard the operating system. It gave a message that

While initiating IOS:
Error: Real mode system memory allocationfailed.

What does this error message ,mean and what was I supposed to do?