Intermittent Data Corruption on RAID

[Snowknight26]

I've recently been noticing corrption in files that are stored on my RAID (16 1TB Seagate on an ARC-1280ML with 2GB ECC RAM, RAID5) that seems to be pretty intermittent. One day I'd watch a movie that's stored on the server and I'd notice terrible corruption. I could confirm the findings on a different computer using a different player. The next day, the corruption would be totally gone but would be present in a different one, and again, day after that, gone. Another example is some with some of the music I have. One day it stops decoding at a certain point but the next day it's perfectly fine.

So I tried to narrow it down to certain files, but that turned out to be fruitless. Nevertheless, in my search for a fix, I found some pretty bizzare things.

G:\Encoding Tools>fciv.exe -both "G:\Music\Sebastian Brandt\Serenade\01 - Serena
de (Original Mix).wma"
//
// File Checksum Integrity Verifier version 2.05.
//
                MD5                             SHA-1
-------------------------------------------------------------------------
8735c501331890cc5de5cf8b6dde2227 3e611c9684bb764eaf776efa0f2c0ae0af6a0e0f g:\mus
ic\sebastian brandt\serenade\01 - serenade (original mix).wma

G:\Encoding Tools>fciv.exe -both "G:\Music\Sebastian Brandt\Serenade\01 - Serena
de (Original Mix).wma"
//
// File Checksum Integrity Verifier version 2.05.
//
                MD5                             SHA-1
-------------------------------------------------------------------------
8735c501331890cc5de5cf8b6dde2227 8b609e9770868928ea174c47eb8d168b716251d5 g:\mus
ic\sebastian brandt\serenade\01 - serenade (original mix).wma

The first hash check is before I went to Check Volume Set in the Areca configuration thing. After finding one error in the first few minutes of it (4 hours in at the moment or so its only half way), I did the second hash check above and I found that the MD5 sum of the file was the same before and after, but the SHA-1 was different. The latter of the SHA-1 checksums is correct as I compared it to the same file I had copied to an external drive a week or so before.

I guess I'm really looking for several things: Why would there be intermittent data corruption that comes and goes (only noticed it in the last week or so), why the discrepency in the checksums, and is it something I have to be concerned about? Perhaps bad RAM on the controller (though maybe not as it would be spewing errors out left and right)? Would it be safe to run chkdsk /f?

Edit: Just realized that the the MD5 checksum of the file on the external drive is different once again, but the SHA-1 checksum is the same. What's going on?

C:\Users\Admin\Downloads>fciv.exe -both "\\MR_ROBOTO\Black TB #2\Trance\sorted\S
ebastian Brandt\Serenade\01 - Serenade (Original Mix).wma"
//
// File Checksum Integrity Verifier version 2.05.
//
                MD5                             SHA-1
-------------------------------------------------------------------------
a9221a0f3d4e1afe8f9cbb82077fcff9 8b609e9770868928ea174c47eb8d168b716251d5 \\mr_r
oboto\black tb #2\trance\sorted\sebastian brandt\serenade\01 - serenade (origina
l mix).wma

chkdsk log before the Check Volume Set started:

C:\Documents and Settings\Administrator>chkdsk G:
The type of the file system is NTFS.

WARNING!  F parameter not specified.
Running CHKDSK in read-only mode.

CHKDSK is verifying files (stage 1 of 3)...
113040 file records processed.
File verification completed.
1423 large file records processed.
0 bad file records processed.
0 EA records processed.
0 reparse records processed.
CHKDSK is verifying indexes (stage 2 of 3)...
363382 index entries processed.
Index verification completed.
5 unindexed files processed.
CHKDSK is verifying security descriptors (stage 3 of 3)...
113040 security descriptors processed.
Security descriptor verification completed.
7868 data files processed.
Correcting errors in the uppercase file.
Windows found problems with the file system.
Run CHKDSK with the /F (fix) option to correct these.

  14304984 MB total disk space.
  14172784 MB in 61451 files.
     17688 KB in 7870 indexes.
         8 KB in bad sectors.
    965176 KB in use by the system.
     65536 KB occupied by the log file.
 134390264 KB available on disk.

      4096 bytes in each allocation unit.
3662076090 total allocation units on disk.
  33597566 allocation units available on disk.

Check Volume Set finished with only 1 error.

Edit 2: And just for kicks I ran the checksums again on the RAID after its ~52% done checking:

G:\Encoding Tools>fciv.exe -both "G:\Music\Sebastian Brandt\Serenade\01 - Serena
de (Original Mix).wma"
//
// File Checksum Integrity Verifier version 2.05.
//
                MD5                             SHA-1
-------------------------------------------------------------------------
a9221a0f3d4e1afe8f9cbb82077fcff9 8b609e9770868928ea174c47eb8d168b716251d5 g:\mus
ic\sebastian brandt\serenade\01 - serenade (original mix).wma

Not only does the SHA-1 checksum match the external, but this time the MD5 checksum does as well. I'm utterly stumped.