[X] Dualboot cannot start...Urgent please

How is this urgent at all. Your PC doesn't boot, sure. But there is no urgency here.

Boot to the liveCD and reinstall grub2. This may help.

Thank you actionparsnip,
I agree that urgency is a very relative notion.
I am still in a liveCD session. I do however not know how to reinstall grub2. Can you guide me please? I believe that I have at present grub. What is the difference with grub2?
Thank you

Look at: "The Grub 2 Guide (formerly Grub 2 Basics)" - http://ubuntuforums.org/showthread.php?t=1195275

Scroll down to: #13 "Reinstalling GRUB 2 from the LiveCD"

Thank you both actionparsnip and arochester,

It seems -at least up to now- that the problem has disappeared after reinstalling GRUB according to the instructions in #13.
I am grateful.

Thanks arochester, that solved my question.

Too quickly to claim a solution....my abort problem is back after I could start a few times without hinder...
I do not know what is left to try.
Thanks for possible assistance.

So what is the current situation? What happens when you boot the system?

I still get the same message, referring to a failure to start from network:
no module name found
Aborted
Intel UNDI, PXE-2.1 Gigabit Ethernet Controller Series u2.26 (090216)

I started again from the life-cd. Of course I cannot access Win7 neither. Shouldn't I try and reinstall Win7 from the dvd I got? And maybe forget altogether about Ubuntu?

As I explained in previous thread, PXE error message is not an error by itself. Simply in BIOS boot order, network is after internal disk, and as boot on internal disk fail, BIOS try to boot by network. Your problem is with hard disk and not network.
1) Could you confirm that when you boot, sometimes you get Grub menu, and sometimes not ? In this case, you also have an hardware problem.
2) Please, provide to actionparsnip the partition table. It will need this data in the future. And provide also error messages before "PXE" error message. These ones are meaningful.
3) If you need urgently your PC to work. Perhaps best is to recover Seven, do what you have to do, and after, quietly, redo a clean Ubuntu installation. Urgency usually means errors, and lot of work to repair.
I apologize, but currently, I have too many "heavy" questions to manage, so I will let you with actionparsnip.

Thank you all who take a look at my problem.
I am now on my now pc in an usb life session.
Typing sudo parted -l, the response is:

To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo parted -l
Model: ATA WDC WD3200BEKT-7 (scsi)
Disk /dev/sda: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
 1 32,3kB 41,1MB 41,1MB primary fat16
 2 41,9MB 15,8GB 15,7GB primary ntfs boot
 3 15,8GB 129GB 113GB primary ntfs
 4 129GB 320GB 191GB extended
 6 129GB 193GB 64,0GB logical ext4
 7 193GB 315GB 122GB logical ext4
 5 315GB 320GB 5179MB logical linux-swap(v1)

Model: Kingston DataTraveler 2.0 (scsi)
Disk /dev/sdb: 2031MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
 1 31,7kB 2030MB 2030MB primary fat32 boot, lba

Upon restarting the pc, I occasionally get the boot-choice panel and can start or Win7 or Ubuntu, but mostly I get the message which seems to show that the system went to look, in vain, to start from a network:
the same message, referring to a failure to start from network:

no module name found
Aborted
Intel UNDI, PXE-2.1 Gigabit Ethernet Controller Series u2.26 (090216)

In the meantime, in Bios I changed the booting order USB - removable - cd - hdd - network (even then the presence of a life-usb stick on one of the ports was not observed in a couple of start-up occasions; I had to move it to another usb-port...). Would you consider that there really is a hardware problem on my new Dell? This will be hard to transmit to Dell since Win7 seemed to work fine.
Thanks and regards.

I am on an Intel Atom at the moment. I got it as a barebones and it initially wanted to boot from PXE, I am not on a network so I just went into the BIOS, by pressing F2, to change the boot order and DISABLED network boot.

Strangely I only have one boot option listed "the Hard Drive"- but I have no CD-Rom- and create distros on a USB stick using unetbootin or usb-creator. When I put a USB stick IT WILL BOOT.

Maybe you should try disabling everything except the Hard Drive...and see what happens...

I am presently reinstalling Win7 from scratch, with the intention to reinstall Ubuntu 10.04 afterwards from my usb stick. Any good advice at this moment?
Thank you.

Yes, don't use 100% disk space for windows. Leave the space you want to install Ubuntu to UNPARTITIONED. This will make life a LOT easier later and the dual boot will be handled

Thank you actionparsnip,

That's more or less what I did. Win7 worked more or less fine, although some parts, included originally by Dell, were lacking now.

When installing Ubuntu from the usb, I have choosen, following the guidelines which I found in the Ubuntu Linux book from Mark G. Sobell, to make partitions in the free space for swap, /boot, /, /home, /tmp, /usr and /var.
Everything seemed to go smoothly, I updated to the newest files, installed two non-free drivers which were suggested and made up to restore my backed.up data (from my Ubuntu netbook) from an external disk. The last Ati driver requested a restart, which I did. The dreadful message came back again, although now it did not include "no module name found. Aborted" and started right away with "Intel UNDI....", ending with PXE-M0F: Exiting PXE-ROM; Invalid partition table" and remained stuck. Hopeles!
After starting from life-usb (which at first was not observed; I had to plug it into another usb port) and restarting the pc again afterwards, I got back the dual-boot choice.

The outcome of "parted -l" is:
Model: ATA WDC WD3200BEKT-7 (scsi)
Schijf /dev/sda: 320GB
Sectorgrootte (logisch/fysiek): 512B/512B
Partitietabel: msdos

Nummer Begin Einde Grootte Type Bestandssysteem Vlaggen
 1 32,3kB 41,1MB 41,1MB primary fat16
 2 41,9MB 15,8GB 15,7GB primary ntfs opstartbaar
 3 15,8GB 157GB 142GB primary ntfs
 4 157GB 320GB 163GB extended
 5 157GB 161GB 3999MB logical linux-swap(v1)
 6 161GB 162GB 199MB logical ext4
10 162GB 165GB 2999MB logical ext4
11 165GB 284GB 119GB logical ext4
 7 284GB 285GB 999MB logical ext4
 8 285GB 318GB 33,0GB logical ext4
 9 318GB 320GB 2542MB logical ext4

Do you or anyone overthere still have any good idea? Many thanks.

Once more I reinstalled everything, Win7 (with some reduced possibilities) and afterwards Ubuntu 10.04. Before installing, I had made a free section on my hdd. After having Win7 operational, I installed Ubuntu into the free section, 'side by side', letting the installer handle the partitions. Now the system seems to be functional and stable.

I still have no idea what went wrong and why my pc insisted on so many occasions to try and start from a network, in vain of course.

For those interested in this very time consuming process: making separate partitions before installing Ubuntu, following the guidelines in the Ubuntu Linux book by Mark G. Sobell (separate /, /home, /usr, /var, /boot), and telling the 'Déjà Dup restore' to restore my data files into the "original" places, was a bad idea; nothing functioned properly!

Thanks for all assistance.