Issue with MDADM raid 5

I recently put together a large Raid 5 file server.
Computer is running Fedora Core 3. Raid 5 is software raid using mdadm. Because the network here at my house is used by a bunch of semi-literate (just enough to mess things up) people, I run a chown script against the root of the samba share every so often. This has been working fine, but has brought some things to my attention. I am loosing files slowly. The Raid itself is 5 WD 320gig SATA drives. Using a supermicro enclosure and 2 crappy little PCI SATA controller cards. /dev/md1 is formatted as an ext3 file system. I will be getting a nicer controller card in the next few months (moving to a PCI-X architechture, but for now this is all I have).

The errors I'm getting are:

code:
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Message 72:

Date: Fri, 2 Sep 2005 10:30:25 -0400
From: [email protected] <mailto:[email protected]> (Cron Daemon)
To: [email protected] <mailto:[email protected]>
Subject: Cron <root@RIAA> chown -R nobody.nobody /fileserv

chown: cannot access `/fileserv/Audio/Jay's Shit/Rap Hip-Hop/Talib Kweli/Talib Kweli & Hi-tek - Reflection Eternal/010-reflection_eternal-name_of_the_game-ego.mp3': Input/output error
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This file is now GONE. It will show up in an ls, but i can not access said file at all. The only thing I can do with it is rm -f it or run an fsck (on the md device) and it just disappears after the fsck is complete.

/proc/mdstat seems to show everything as ok

code:
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[root@RIAA ~]# cat /proc/mdstat
Personalities : [raid5]
md1 : active raid5 sde1[4] sdd1[1] sdc1[0] sdb1[3] sda1[2]

    1250274304 blocks level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]

unused devices: <none>
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Do I have a bad drive? Or is something else going on here? Need more info? Just ask, I'll provide what I can.

PS: I sent this twice, I posted it on a forum that I frequent, and realized that I had left a bad word or two in when I sent it to the list. Sorry if you get it twice (hopefully the first gets filtered out somehow), and if the bad word offends, this is the cleaner version. I guess I should not write long emails at 12:42am