Installer error when booting up computer (using Windows XP SP3)

Hello experts.
I am using Windows XP Pro Service Pack 3. Everything was working perfectly before until recently. During the last two bootups, I got the following error message. I have added an image but the image is too little, and you might not read it properly. It says:
Installer.exe
Installer.exe has been encountered a problem and needs to close. We are sorry for the inconvenience
If you were in the middle of something, the information you were working on might be lost.
Please tell Microsoft about this problem
We have created an error report that you can send to us. We will treat this report as confidential and anonymous.
To see what data this report contains, click here.
I have to solve this problem. Please help. Thanks a lot.
