cant find lvm volumes at boot

hi all,

I've been running LVM2 for a while and never had any problems with it, so my knowledge is a bit limited because i've never had to fiddle with it. It started with me wanting to change my hda drive cuz the old one was making alot of noice.
It's partitioning sheme is as follows

  /dev/hda1  [      101.94 MB]    /boot
  /dev/hda2  [        1.87 GB]    /
  /dev/hda3  [       23.00 GB]    LVM physical volume
  /dev/hda4  [      533.90 MB]    SWAP

--- Physical volume ---

  PV Name               /dev/hda3
  VG Name               vgsys
  PV Size               23.00 GB / not usable 0   
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              5888
  Free PE               0
  Allocated PE          5888
  PV UUID               SegkSC-Thbb-DqRg-LSoA-tN0F-WmFp-K7CPCO

--- Logical volume ---

  LV Name                /dev/vgsys/usr
  VG Name                vgsys
  LV UUID                cYrDRH-neMm-PwCZ-2Dlo-njJm-mBHs-NPZlu4
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                7.00 GB
  Current LE             1792
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:0

--- Logical volume ---

  LV Name                /dev/vgsys/home
  VG Name                vgsys
  LV UUID                OX1Pkm-p6Vc-q6SB-9nxm-PRMl-TM1z-h5bcIc
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                4.00 GB
  Current LE             1024
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:1

--- Logical volume ---

  LV Name                /dev/vgsys/opt
  VG Name                vgsys
  LV UUID                GlQ5wV-ZzUu-51LW-okn6-82UV-9SFX-weiScV
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                5.00 GB
  Current LE             1280
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:2

--- Logical volume ---

  LV Name                /dev/vgsys/var
  VG Name                vgsys
  LV UUID                1VvzOf-DLz1-GMp5-Xj24-r9Mp-yaOy-0t2yLw
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                5.00 GB
  Current LE             1280
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:3

--- Logical volume ---

  LV Name                /dev/vgsys/tmp
  VG Name                vgsys
  LV UUID                BAIl2N-5gVg-RzUZ-3IqL-L0D5-JiAk-bO2smA
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                2.00 GB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:4

Then i added a new 80GB drive at hdc and run

dd if=/dev/hda of=/dev/hdc

then halt -h

changed disks and booted with the new 80GB disk as hda...
now the strange thing...it cant find the logical volumes at boot, so i end up with a very crippled system. if i list the lvm volumes i see that they are there, but inactive at boot. i can reactivate them and mount them manually...but then at reboot the same thing again. what have happened?
I even tried to change back to the old drive, and i was certain it would boot right up...but the exact same thing occured. GAAAH! How can the source drive be altered? I don't get it.
Any ideas?

thanks!

/Fredrik