Windows startup problem

When I turn on my computer, I get the message that I do not have enough memory to run windows. It suggests looking at config.sys or autoexec.bat, or eliminating memory resident programs, or checking drivers. It then says press any key, and once pressed, it says it is now safe to turn off your computer. Then I switch off the computer power, and start it up again, and it asks me what mode I want to run in. I hit normal, and it starts up fine.