I have been using Ext2fsd for some time (over a year) without issue (at least nothing more than timestamp issues) on two of my computers. I mostly use Ext2fsd with my data partition (drive L:) so I can access my data from both Windows and Linux. I have also been installing Windows program files on L: as I do not have much room on my OS partition. Lately I have installed Steam (http://store.steampowered.com/) on two of my computers along with several gigabytes with of games on my data paritions (L:). On both computers, soon after I installed Steam and some games, I have received data corruption errors from fsck which indicate that files are sharing blocks in addition to other less critical errors. If this did not occur on both of my computers, I would not suspect a problem with Ext2fsd. I suspect that Steam is using some Windows file system feature that is not properly implemented by Ext2fsd.
To confirm that actual data corruption occurred, I happened to have an md5sum of one of the files that fsck reported as sharing a block. The md5sums of the file no longer match.
I am using version .46 on both computers. I am using Kubuntu 8.04 (AMD64) with ext3 on my Laptop and Gentoo Linux (AMD64) with ext3 on my Desktop. Both computers are also running Windows XP Professional - 64 Bit Edition.
Unfortunately I do not have a fsck log file for you. I am willing to do more testing (with a scratch partition) to help you resolve this issue. Reply to this error report if you need any assistance.