After unsuccessfully trying to get bitcoin-qt running again by deleting the most recent blockchain files, I simply uninstalled the whole program, restarted the computer, deleted everything in C:\Users\BZ\AppData\Roaming\Bitcoin, and reinstalled a fresh copy of 0.8.1. The block chain sync had been running for several hours, and I had about 30,000 more blocks to go, when it crashed again in exactly the same way.
This seems like a pretty serious problem. Are there any other reports of this or known solutions?
Bitcoin version v0.8.1-beta (2013-03-17 15:35:36 -0400)
Using OpenSSL version OpenSSL 1.0.1c 10 May 2012
Startup time: 2013-04-03 04:10:56
Default data directory C:\Users\BZ\AppData\Roaming\Bitcoin
Used data directory C:\Users\BZ\AppData\Roaming\Bitcoin
Using 4 threads for script verification
init message: Verifying wallet integrity...
dbenv.open LogDir=C:\Users\BZ\AppData\Roaming\Bitcoin\database ErrorFile=C:\Users\BZ\AppData\Roaming\Bitcoin\db.log
Bound to [::]:8333
Bound to 0.0.0.0:8333
init message: Loading block index...
Opening LevelDB in C:\Users\BZ\AppData\Roaming\Bitcoin\blocks\index
Opened LevelDB successfully
Opening LevelDB in C:\Users\BZ\AppData\Roaming\Bitcoin\chainstate
Opened LevelDB successfully
LoadBlockIndex(): last block file = 22
LoadBlockIndex(): last block file: CBlockFileInfo(blocks=1468, size=131813551, heights=197723..199190, time=2012-09-07..2012-09-17)
LoadBlockIndex(): transaction index disabled
LoadBlockIndex(): hashBestChain=000000000000037df60961cceb00c3c1fbd92b382a712064159c30132762dd7c height=199189 date=2012-09-17 10:06:07
init message: Verifying block database integrity...
Verifying last 288 blocks at level 3
No coin database inconsistencies in last 289 blocks (49187 transactions)
block index 10624ms
init message: Loading wallet...
nFileVersion = 80100
wallet 780ms
init message: Importing blocks from block database...
LevelDB read failure: Corruption: block checksum mismatch
*** System error: Database corrupted
init message: Loading addresses...
Loaded 12193 addresses from peers.dat 63ms
RandAddSeed() 173316 bytes
mapBlockIndex.size() = 199191
nBestHeight = 199189
setKeyPool.size() = 100
mapWallet.size() = 0
mapAddressBook.size() = 1
send version message: version 70001, blocks=199189, us=0.0.0.0:0, them=0.0.0.0:0, peer=127.0.0.1:0
init message: Done loading
EnvShutdown exception: Invalid argument (22)