Post Beep Codes-I need Help

I have a Compaq Desktop Pro that I was just putting a CD ROM in and after I installed the CD ROM and started the machine, I got the following beep code during the POST:
1L, 1S, 1L, 1S, 1L, 2S L=long S=short

Can anyone help me out and tell me what my issue is? I tried looking it up and I have one that says that if is 1L 1S that it is a Motherboard issue, but I am just thinking its not. Also as for my brand of Motherboard, I am not sure it says Compaq on it!
Any help would be appreciated!