External drive problems- iTunes 9 ...

I have a very large library (~27,000 items) on an external drive (USB 2.0).
Since installation of iTunes 9.0 the drive has been ejecting when iTunes starts up.
After iTunes runs (w/spinning beachball) for about 20 seconds, the volume I keep my library on will disappear from the Devices list in the Finder.
Then iTunes will report that it's analyzing for gapless playback.
Then it will stop and all of my tracks will be marked as missing (with the dreaded 'x').

My system log reports the following:

Sep 9 18:31:11 Oculus mds41: (/Volumes/Sounds/.Spotlight-V100/Store-V1/Stores/DB0BEF9F-5DBC-4E02-8575-5BFDBB94521D)(Error) IndexStore in SIStoreDirytySDBChunks:Error storing dirty sdb pages: 22
Sep 9 18:31:11 Oculus kernel[0]:
Sep 9 18:31:11: --- last message repeated 2 times ---
Sep 9 18:31:11 Oculus mds41: (/Volumes/Sounds/.Spotlight-V100/Store-V1/Stores/DB0BEF9F-5DBC-4E02-8575-5BFDBB94521D)(Error) IndexCI in _ContentIndexSyncIndexBulk:preSync error:22 22
Sep 9 18:31:11 Oculus kernel[0]:
Sep 9 18:31:11: --- last message repeated 6 times ---
Sep 9 18:31:11 Oculus 0x0-0x2e02e.com.apple.iTunes388: 2009-09-09 18:31 iTunes388 (CarbonCore.framework) process_dir_events: KEV: UNKNOWN EVENT: ident 0x1e filter 0xfffffffc flags 0x8031 fflags 0x0 (0)
Sep 9 18:31:11 Oculus 0x0-0x2e02e.com.apple.iTunes388: 2009-09-09 18:31 iTunes388 (CarbonCore.framework) process_dir_events: KEV: UNKNOWN EVENT: ident 0x1f filter 0xfffffffc flags 0x8031 fflags 0x0 (-2147483648)
Sep 9 18:31:11 Oculus 0x0-0x2e02e.com.apple.iTunes388: 2009-09-09 18:31 iTunes388 (CarbonCore.framework) process_dir_events: KEV: UNKNOWN EVENT: ident 0x20 filter 0xfffffffc flags 0x8031 fflags 0x0 (-2147483648)

The first messages refer to the disk "Sounds" which is the disk that keeps ejecting, and a spotilight error(?).
The second messages refer to iTunes.

Any ideas about the meaning of these?

I notice others with external drives are having issues, but haven't read an account like mine quite yet.

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Orignal From: External drive problems- iTunes 9 ...