hi. i had a working multi-boot system, vista on sda1,2; swap sda3; ext=sda4; ubuntu sda5; fedora sda6; data sda7 - i mount the data partition when using all of the linux releases so i don't have to have multiple copies of music, docs, etc. everything has worked fine until yesterday. i tried to install fc12 on sda6, replacing fc11. it required me to format sda6 as ext4. i wasn't sure where i had grub installed, but have a backup of menu.lst in data (sda7), so figured i could let it install to mbr or wherever it wanted to by default.
when the install completed and i reboot, i get a black screen and these messages: CLIENT MAC ADDR: 00 19 XX XX XX GUID: XXXXX PXE-E53: No boot filename received
PXE-M0F: Exiting Intel Boot Agent.
No bootable device -- insert boot disk and press any key
I tried reinstalling fc12, same exact errors.
I then thought maybe the problem had something to do with ext4 partition mixed in with ext3's, so i installed mepis on the sda6, and let it write grub to mbr (i think, not really sure where it wrote it).
anyway, i still get the identical black screen. no grub type menu or anything. the screen used to show "DHCP for a few seconds", but doesn't anymore after i disconnected the ethernet cable.
i was thinking when i originally did the shrink partitions in vista to allow me to dual boot, i had to be extra careful as to where to put grub and/or the mbr, but i can't remember since it was months and months ago.
my guess is i have hosed up grub and/or mbr, but am hopeful i can recover without wiping the hd. right now i have it booted with a ubuntu live 8.x and have ran fdisk -l. it shows all the partitions. sda6 has * under the Boot column.
i would really appreciate some help in getting this up and running without having to reload vista and also don't want to lose the linux partitions if possible. thanks for your help.

Maybe you accidentally changed a BIOS setting so it isn't booting from the HD at all. Maybe when there is no CD to boot from, it is going into some network boot rom.

Check the BIOS menu for boot settings.

0. go to your bios settings and put in the right boot sequence ... disable network boot

if you still have a problem

1. rescue ubuntu with the ubuntu cd/dvd and install grub to mbr.

am sure i didn't change the boot seq in bios. never go into bios. when i did go in there, i changed it back to defaults. it is set to boot from cd, then hd.

Interesting - I had similar happen on an old laptop a couple of years back. After a Ubuntu re-install. Just stopped booting.
I set up a boot floppy, but soon got sick of that. Gave me incentive to go get a new laptop.
Not much help to you ...

i solved this problem by using the Vista Recovery CD and repairing the system files. it ran in just a few seconds, and made the first partition bootable.