Thanks for your response osilaya. Since my post, I've received the following (after a reboot):
Source: ESE97
Categ: Logging/Recovery
Evt ID: 0
Desc: MSExchangeIS (2668)-1022
Then;
Source: MSExchangeIS
Categ: General
Evt ID: 1120
Desc: Error Disk IO error initializing the MS Exchange Information Store database.
Then;
Source: MSExchangeIS
Categ: General
Evt ID: 5000
Desc: Unable to initialize the MS Exchange Information Store service. Error Disk IO error.
Then (sorry);
Source: ESE97
Categ: Performance
Evt ID: 0
Desc: MSExchangeIS (2688) Unexpected Win32 error: 0x21
Finally repeating;
Source: MSExchangeIS
Categ: General
Evt ID: 1159
Desc: Database error Disk IO error occurred in function JTAB_BASE::EcSetColumn while accessing the database.
Now I know what you're thinking - DiskIO is the problem. Well I contacted HP support and we went through the System Log, the IMLs and the ACU and they insist that there is nothing wrong with those drives and definitely nothing that would justify a replacement. The logical drive in question, is actually 3 physical drives in a RAID5 array within an external SAN drive enclosure (with 9 other physical drives). The only difference I could find, was that under the Insight Management Web Interface, ONE drive in the enclosure registered 7 under "Other Timeouts" in the "Problem Indicators" section. This however doesn't yield much because the recommended tests are very generic (ensure cables plugged in, etc). I was wondering, is it possible that something is wrong at the Windows (2K) or even Exchange (database) level? Is it possible that the physical hardware is operating properly, but being incorrectly blamed by the OS or Exchange?
What other steps can I take to investigate? In the meantime, I'll swap the drive with the 7 "other timeouts" with a different drive in another slot. This may eliminate the drive or the slot from the list of possibilities.
Thanks again for your help!
sake