If all that is on a black screen with white letters, before it EVER gets to the operating system (windows, etc), that DHCP message with the spinning character indicates your machine is trying to boot from the network card. -This condition could return if you don't hunt it down. It could be because your hard drive is not connected well, so the BIOS skips the HD and goes on to the next boot device specified until it finds something, ie; the Network card, which tries to find a DHCP server to establish it's IP address and thus start booting from a network.
Things to check:
CMOS Battery -seated properly or dead/needs replacement.
Hard drive connections -make sure all connections are seated properly to the drive and the motherboard.
BIOS Boot order - make sure HD is first in list (or second, after CDROM). -If Network Card is in boot order, see if you can remove it.
The Network card is intergrated to the mobo and will not have become loose. I imagine the Modem is, too, and you don't boot from a modem, anyway.
