serious problem with MBR

[Vincent GUYOT]

Hello,

I send you all this email, hoping an answer before formatting my hard drive :(
To GRUB specialists (developpers & so): if you never heard about this, tell 
me. May be isn't it because GRUB.

the background:
I'm used for few years to boot my PC under Linux with lilo, but since I 
upgraded my system few months ago with Mandrake 7.2 distro I use the GRUB now.
I swap between Linux & Window$98 systems and my hard drive is divided into 4 
partitions, 2 partitions FAT32, 1 Linux swap & 1 ext2fs.

the problem:
I switched ON my computer, nothing on the screen but "GRUB >", MBR seemt 
corrupted. Booting with Win98 CDROM, I did "c:\fdisk /mbr" to restore a 
usable MBR, thinking about re-install the GRUB later.
Then, I booted again, with my virgin MBR. Win98 works, but D: partition is no 
more there! My Linux partitions also seem go away!

panic:
I tried to boot with linux distro CDROM: "no valid linux partition found" (or 
something like that)
I tried the well-known Partition Magic software: 1 partition found, other 
space is marked "unformatted".

question:
is it a known GRUB'bug?

why this email:
it is the second time I got this problem, 2 times on a system I just (few 
month before) installed GRUB & no more lilo. 
Then, I think it's may be GRUB'fault. But may be am I wrong, I didn't noticed 
anything in the mailing-list's archives.
The 1st time, I had a backup of the system, but now I have valuable data on 
the D: ghost-partition & scare have all lost.

Don't hesitate to email me, even just:
"I follow GRUB developpement & never heard about that, sorry dude".
thanks to have read this email.

Vince

PS: forgive my "french" english