ok, here some more information:
when I run rescue-gui and say lsparts I get a list of all my partitions saying that the ext2 or root-partition is on sda6
after reinstalling bootlaoder lilo.conf has only sda6 entries finally, but the fstab still looks like this:
# This file is edited by fstab-sync - see 'man fstab-sync' for details
/dev/sda7 / ext2 defaults 1 1
/dev/hda /mnt/cdrom iso9660 user,iocharset=iso8859-15,noauto,ro,exec 0 0
none /mnt/floppy supermount dev=/dev/fd0,fs=ext2:vfat,--,umask=0,iocharset=iso8859-15,sync,codepage=850 0 0
/dev/hdb5 /mnt/win_c vfat umask=0,iocharset=iso8859-15,codepage=850 0 0
/dev/sda1 /mnt/win_c2 ntfs umask=0,nls=iso8859-15,ro 0 0
/dev/hdb6 /mnt/win_d vfat umask=0,iocharset=iso8859-15,codepage=850 0 0
/dev/sda6 /mnt/win_d2 vfat umask=0,iocharset=iso8859-15,codepage=850 0 0
none /proc proc defaults 0 0
/dev/sda5 swap swap defaults 0 0
So right now I'm not sure if ext is on sda6 or sda7 anymore. It can't find it on sda7 so I'm assuming that it just isn't there. On the other hand how would the fstab get changed, switching the two drives aroudn like that (sda7 and sda6). Is it possible that somehow the names where switched (rearranged in the partition table...)? Or did some configuration just change the lilo and the fstab files? What may have caused this strange behaviour?
Is there a way to fix it or should I just format the linux partitions and reinstall?