I had this FAT32 partition which I wanted to convert to EXT3.
FAT32 is in the category of DOS 6 partitions mentioned on the man page. So you modified a DOS6 partition.
I'm not 100% sure that this does apply, but let me explain what I think may have been the problem.
Using fdisk you converted the FAT32 to type ext3 and then did an mk2efs on that partition.
In the partition table there is enough information to tell linux that it is an ext3 partition, so everything is sweetness and light.
When you went back to Windoze, the Windoze system reads the partition table and looks for more information than is used by linux or is written by FDISK. The size of the partition is contained in there as well. Let me illustrate very crudely
Partition table info -- purely illustrative -- highly inaccurate
before <this is a FAT32 partition><size of partition><who knows what else other info>
fdisk merely changes this to
after <this is ext3 parition><this is same as above><this is same as above>
So Windoze sees some strange information about ext3, but the
rest of the size of the parition info is still intact and anything else
So being clever, it tries to repair it.
A better example is when you try to resize a partition with fdisk eg
before : hda1 8 GB
fdisk change to 4 GB
linux reports file system size as 4 GB
Go back to Windoze, and it will tell you the size is 8 GB
If you try and use it, Windoze will overwrite files in your ext3 filesystem.
Use Format C: and it will format it as 8 GB
This is why you have to use dd to wipe out that other Windoze related information in the partition table information.
The only reason I know about this, is because I found out by hard experience .... :+}
So what you need to do is,
1) do you have any vital data on the parition which you converted
from FAT32 to ext3?
2) if so and you are runnign windoze, stop immediately and
boot into Linux
3) backup those essential files from that partition to another
4) umount the problem partition
5) dd if=/dev/zero of=/dev/hd<problem partition> bs=512 count=1
6) mke2fs -j -L parition_name /dev/hd<problem_partition>
7) fsck /dev/problem_partition
8) mount /dev/problem_partition
9) unpack your tar archive of vital data
10) hopefully everything should be okay now
even with Windoze not trying to mess around with it