After win erased my mbr I went to reinstall grub but now it says it cant mount the root unknown filesystem 0x8e

I have a LVM partision on the disk but / and /home is ext3 and it booted fine before.

Mount and chroot on the disk works fine, is there anything special I need to do when I have LVM partisions and installing grub? Im kinda new to this LVM stuff.

fdisk:
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 2432 19535008+ 83 Linux
/dev/sdb2 2433 2614 1461915 82 Linux swap / Solaris
/dev/sdb3 2615 12340 78124095 83 Linux
/dev/sdb4 12341 38913 213447622+ 8e Linux LVM

Extra info:
Debian etch kernel 2.6.18 amd64 SATA-disks, cant think of anything else that could be relevant.

If no one is gonna throw me a bone here I'm gonna try to make it boot as LVM even tough it's not. I read that LVM stuff needed to be loaded in RAM before it can mount the disk, so I'll try that. Just think its a little strange that it booted fine whit the same initrd image before (thats the ram disk image right?)
Even though I'v used linux for over two years now I still feel like a newbie

If anyone has any better info on this problem plz reply, I'll be happy to provide any info/output you may need to help me trubbleshot this.

PS: sorry for my crap english.

Solved it. I had reinstalled grub to (hd2) as my root is (hd2,0) but it needed to be installed in (hd0)