I have a Dell Desktop Dimensions e310.  It runs on the Windows XP operating system.  The other day when I tried to turn on the computer, it beeped several times and the 1 & 2 diagnostic lights were off and the 3 & 4 lights stayed on and the computer would not boot up.  I have 2 module connectors-A on the bottom and B on top.  I have 2 512mb memory modules (I'll call them #1 and #2).  I read the owners manual which said to remove the memory modules one at a time to see if one is defective.  I turned the computer off and removed both modules.  I placed #1 in slot A and the computer turned on.  I turned it off and took out #1 and replaced it with #2 in slot A and the computer turned on.  So it appears there is not a deffective memory module.  I then turned the computer off and put #1 in slot A and #2 in slot B.  The same diagnostic light pattern occurred and the computer would not boot up.  I turned the computer off again and switched #1 into slot B and #2 into slot A.  After hitting the power button, the same diagnostic light pattern occurred and the computer would not boot up.  It seems that the problem is the Slot B memory module connector.  These memory modules have been in since I bought the computer.  They have never been changed or removed since I bought it so I don't know how the connector could have been damaged.  Does anyone have a suggestion on what else could be wrong and how to correct it?  If if is the connector, how do I go about replacing it.  Would I have to replace the entire mother board?  Thanks in advance to anyone who responds to this inquiry.