pre-installed win7. installed U10.10 now won't boot

In further investigating the boot sector partition, I find no sign of grub at all--only the windows BCD program, logs and 'bootmgr'

I guess I have to reinstall grub2...?

Windows may have nuked grub's mbr during update :( If true, then thats pretty nasty.

Have a look at this:
https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB%202

Try to reinstall Grub, it fixes lot of such issues:
   https://help.ubuntu.com/community/Grub2#Reinstalling%20from%20LiveCD

I followed method 1 (copy from livecd) at:
https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB%202

When I rebooted, it again failed.

Upon rebooting from the livecd, I fount that the boot partition had a grub folder as well as the boot folder & BCD stuff.

I'm trying the 2nd method next...

method 2 failed to boot also.

now trying chroot (#3)

Using chroot method 3, I get an error when running "sudo grub-install -recheck /dev/sda"
err:
sudo: unable to resolve host ubuntu #followed by
Installation finished. No error reported.

if I rerun the check, the resolving error does not reappear...

Please provide partition table.

If you can't boot from hard drive, boot en Ubuntu CD/USB stik and then choose "Try without install".

Open a terminal: you can either press Ctrl+Alt+T or Applications->Accessories->Terminal.

To copy/paste in a terminal, replace Ctrl+C by Ctrl+Maj+C and Ctrl+V by Ctrl+Maj+V (for historical reason, Ctrl+C is assigned another function).

Paste to terminal one of the following commands:

    sudo fdisk -l

    sudo parted -l

where "-l" is lower case "L".The two commands provide data in a slightly different format.

Copy/paste result into a new thread post.

Here,s the partition data.

ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x9b5ad714

   Device Boot Start End Blocks Id System
/dev/sda1 1 2350 18874368 27 Unknown
/dev/sda2 * 2350 2363 102400 7 HPFS/NTFS
/dev/sda3 2363 36301 272602231 7 HPFS/NTFS
/dev/sda4 36301 60802 196804609 5 Extended
/dev/sda5 36301 59803 188782592 83 Linux
/dev/sda6 59803 60802 8020992 82 Linux swap / Solaris
ubuntu@ubuntu:~$ sudo parted -l
Model: ATA Hitachi HDT72105 (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number Start End Size Type File system Flags
 1 1049kB 19.3GB 19.3GB primary ntfs diag
 2 19.3GB 19.4GB 105MB primary ntfs boot
 3 19.4GB 299GB 279GB primary ntfs
 4 299GB 500GB 202GB extended
 5 299GB 492GB 193GB logical ext4
 6 492GB 500GB 8213MB logical linux-swap(v1)

Warning: Unable to open /dev/sr0 read-write (Read-only file system). /dev/sr0
has been opened read-only.
Error: /dev/sr0: unrecognised disk label

I,m about ready to start from scratch.... :(

When you tried to reinstall, did you use commands:
    sudo mount /dev/sda5 /mnt
    sudo grub-install --root-directory=/mnt/ /dev/sda

Yes.

Looks strange!
You said you have three identical computers, so of it worked on two of them, it should work on third.
Could you confirm that hardware configuration is the same on all computers (including BIOS version) ?
You have a partition table in first sector of disk, so you should also have a boot code of three hundreds of bytes in this.
Could you run command:
     sudo od --read-bytes=512 --format=x2 /dev/sda
and post result

hardware check will be a few minutes....

ubuntu@ubuntu:~$ sudo od --read-bytes=512 --format=x2 /dev/sda
0000000 63eb d090 00bc 8e7c 8ec0 bed8 7c00 00bf
0000020 b906 0200 f3fc 50a4 1c68 cb06 b9fb 0004
0000040 bebd 8007 007e 7c00 0f0b 0e85 8301 10c5
0000060 f1e2 18cd 5688 5500 46c6 0511 46c6 0010
0000100 41b4 aabb cd55 5d13 0f72 fb81 aa55 0975
0000120 c1f7 0001 0374 46fe 6610 8000 0001 0000
0000140 0000 0000 faff 9090 c2f6 7580 b202 ea80
0000160 7c74 0000 c031 d88e d08e 00bc fb20 64a0
0000200 3c7c 74ff 8802 52c2 17bb 8004 0327 0674
0000220 88be e87d 011c 05be f67c 80c2 4874 41b4
0000240 aabb cd55 5a13 7252 813d 55fb 75aa 8337
0000260 01e1 3274 c031 4489 4004 4488 89ff 0244
0000300 04c7 0010 8b66 5c1e 667c 5c89 6608 1e8b
0000320 7c60 8966 0c5c 44c7 0006 b470 cd42 7213
0000340 bb05 7000 76eb 08b4 13cd 0d73 c2f6 0f80
0000360 d084 be00 7d93 82e9 6600 b60f 88c6 ff64
0000400 6640 4489 0f04 d1b6 e2c1 8802 88e8 40f4
0000420 4489 0f08 c2b6 e8c0 6602 0489 a166 7c60
0000440 0966 75c0 664e 5ca1 667c d231 f766 8834
0000460 31d1 66d2 74f7 3b04 0844 377d c1fe c588
0000500 c030 e8c1 0802 88c1 5ad0 c688 00bb 8e70
0000520 31c3 b8db 0201 13cd 1e72 c38c 1e60 00b9
0000540 8e01 31db bff6 8000 c68e f3fc 1fa5 ff61
0000560 5a26 be7c 7d8e 03eb 9dbe e87d 0034 a2be
0000600 e87d 002e 18cd feeb 5247 4255 0020 6547
0000620 6d6f 4800 7261 2064 6944 6b73 5200 6165
0000640 0064 4520 7272 726f 0a0d bb00 0001 0eb4
0000660 10cd 3cac 7500 c3f4 d714 9b5a 0000 2000
0000700 0021 fe27 ffff 0800 0000 0000 0240 fe80
0000720 ffff fe07 ffff 0800 0240 2000 0003 fe00
0000740 ffff fe07 ffff 2800 0243 28ee 207f fe00
0000760 ffff fe05 ffff 57fe 22c2 0002 1776 aa55
0001000

delance@delance-desktop:~$ diff me.mbr wizodd.mbr
3c3
< 0000040 bebd 8007 007e 7c00 0f0b 1085 8301 10c5
---
> 0000040 bebd 8007 007e 7c00 0f0b 0e85 8301 10c5
28,33c28,32
< 0000660 10cd 3cac 7500 c3f4 e0c8 2c34 0000 0100
< 0000700 0001 fe27 ffff 003f 0000 1f20 0180 fe80
< 0000720 ffff fe07 ffff 1f5f 0180 6267 2412 fe00
< 0000740 ffff fe83 ffff 81c6 2592 9dbf 1e84 fe00
< 0000760 ffff fe83 ffff 1f85 4417 4f3c 066e aa55
< 0001000
---
> 0000660 10cd 3cac 7500 c3f4 d714 9b5a 0000 2000
> 0000700 0021 fe27 ffff 0800 0000 0000 0240 fe80
> 0000720 ffff fe07 ffff 0800 0240 2000 0003 fe00
> 0000740 ffff fe07 ffff 2800 0243 28ee 207f fe00
> 0000760 ffff fe05 ffff 57fe 22c2 0002 1776 aa55

Your and mine MBR differs only at end, which is partition table and at address 4A.
You boot on 5th partition of sda and me at first of sdb. The code of MBR must include address of partition which holds "/boot" folder.
You 0e => 0=sda, 0xe=14 ??? 4th extended partition + 2*5 ???
Me 10 => 1=sdb, 0=1st partition ???
It seems your MBR is sensible, and you have one of Grub2.

For the moment, I have no idea.

Well, I've run out of time and willl wipe the install andtry again.

Thank you very much for your assistance!