I have a problem with Vista startup and all attempts with bootrec and
bootsect failed. Startup repair detects C: drive and detects Vista Ultimate.
Repair says it did not find any problem. When starting up machine I get
black screen without any error message. Issue seems to be similar to cloning
hard drive as I found on the net. If I rename bootmgr I don't get any error
message so it looks like MBR doesn't even transfer control to boot sector.
Disk signature seems to be fine and matches the one I found in registry in
HKLM\SYSTEM\MountedDevices.
I don't seem to be able to find when on the disk I can find GUID which is in
BCD. When I write boot sector by bootsect /nt60 C: it generate GUID which
doesn't match to one generated by bootrec /rebuildbcd.



Do I have to update GUID manually in BCD to match the one generated for
volume by "bootsect /nt60 C: " ?

Now I'm trying to verify boot partition. I dumped first 26kB of data from
boot sector of partition 1 (C: drive) and I'm trying to compare it to copy
of the sector in "Unallocated" space. From those hundred pages of data I can
see only following differences:


Partition 1:
=========
0x00100000 EB 63 90 4E 54 46 53 20 : 20 20 20 00 02 08 00 00 .c.NTFS
......
0x00100010 00 00 00 00 00 F8 00 00 : 3F 00 FF 00 00 08 00 00
.........?.......
0x00100020 00 00 00 00 80 00 80 00 : E8 C7 55 0F 00 00 00 00
...........U.....
0x00100030 00 00 0C 00 00 00 00 00 : 7F 18 2A 01 00 00 00 00
...........*.....
0x00100040 F6 00 00 00 01 00 00 00 : F6 BF 30 FA E8 30 FA 9C
...........0..0..

0x001024A0 AE A9 B1 23 08 01 00 00 : A0 04 00 00 00 00 00 00
....#............

0x001024F0 01 01 00 00 00 00 00 05 : 12 00 00 00 80 FA FF FF
.................
0x00102500 63 00 6B 00 01 01 00 00 : 00 00 00 05 12 00 00 00
c.k.............


Unallocated space:
================
0x1EABA00000 EB 52 90 4E 54 46 53 20 : 20 20 20 00 02 08 00 00 .R.NTFS
......
0x1EABA00010 00 00 00 00 00 F8 00 00 : 3F 00 FF 00 00 D0 55 0F
.........?.....U. Shouldn't I replace D0 55 0F by 08 00 00
(start of the partition C: ?
0x1EABA00020 00 00 00 00 80 00 80 00 : FF BF 4B 03 00 00 00 00
...........K.....
0x1EABA00030 00 00 0C 00 00 00 00 00 : FF BB 34 00 00 00 00 00
...........4.....
0x1EABA00040 F6 00 00 00 01 00 00 00 : F8 AE 20 86 F3 20 86 3C ..........
... .<

0x1EABA024A0 8E B5 59 5A 08 01 00 00 : A0 04 00 00 00 00 00 00
...YZ............

0x1EABA024F0 01 01 00 00 00 00 00 05 : 12 00 00 00 39 36 44 39
.............96D9
0x1EABA02500 44 30 41 39 01 01 00 00 : 00 00 00 05 12 00 00 00
D0A9............


Why do I see these differences? Should they match to the last byte? Is there
any detailed description of boot sector for Vista?

Hi Robert !
Let me guess what happened ... you accidentally installed grub in the Vista bootsector, and then tried to recover with bootsect, didn't you ? Well I did, and I got exactly the same problem you reported. Apparently, there is a bug in bootsect, which does not repair the 3 first bytes of the bootsector - they are just a JUMP for the real bootsector code. EB 63 90 is the beginning of grub's bootsector. The correct beginning should be EB 52 90, which will provide the jump to the Vista bootsector. What I did in my case. I used an hex editor to edit the partition and changed 63 to 52. After that, I rebooted, and my Vista went back, working like a charm. I hope it works for you too.
If you need more information on the Vista bootsector, you may find it in Windows Vista Volume Boot Record (VBR)
where I got the information which solved my problem.