I put my laptop on standby. Later when opening it says:

We apologize for the inconvience, but Windows didn't start sucessfully. A recent hardware or software chage may have caused this.
(other than putting it on standby nothing has been changed)

It carries on and says to try and start on :
Safe mode
Safe mode with Networking
Safe mode with command Prompt
Last known good configuration

Star windows normally

None of these work. After it tries to boot (at the windows xp screen), a blue screen will flash and it goes back to to the Dell screen. At the top it has F2 Setup F12 Boot Menu. I have tried all in the F12. Nothing is working. It just goes back to the we apologize for the inconvenience screen. Please someone help me :)

This has happened to me also couple of months back. Then I have formatted my system and re-install my windows. After that it is working fine. Just try the same and I would suggest one thing to take the backup of all your relevant data by running it on safe mode first.

This problem seems the same as the PC keep rebooting when clicking on the logon logo in XP.

Reinstall the XP works, the system has been infected by the virus and the XP needed to be reinstalled.

Try use the HDD on other PC as a slave drive, then format and reinstall XP.

Hope this helps!
Bill

Insert ur XP Cd and try to "Repair" the installation.