Same problem, immediately upon upgrading from bitcoin-0.8.0rc1-win32 to 0.8.1, on Win7-64.
Chose Cancel. The .sst file referenced did not exist, but no problem creating the .sst file with Cygwin "touch". Deleted the .sst file I had created, restarted Bitcoin-Qt, ran fine the second time, no further mention of .sst files in the debug.log. 2-month old SATA laptop drive with no problems.
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: 2013-03-20 12:52:37
Default data directory C:\Users\username\AppData\Roaming\Bitcoin
Used data directory C:\Users\username\AppData\Local\LargeDB\Bitcoin
Using 4 threads for script verification
init message: Verifying wallet integrity...
dbenv.open LogDir=C:\Users\username\AppData\Local\LargeDB\Bitcoin\database ErrorFile=C:\Users\username\AppData\Local\LargeDB\Bitcoin\db.log
Bound to [::]:8333
Bound to 0.0.0.0:8333
init message: Loading block index...
Opening LevelDB in C:\Users\username\AppData\Local\LargeDB\Bitcoin\blocks\index
Opened LevelDB successfully
Opening LevelDB in C:\Users\username\AppData\Local\LargeDB\Bitcoin\chainstate
Opened LevelDB successfully
LoadBlockIndex(): last block file = 14
LoadBlockIndex(): last block file: CBlockFileInfo(blocks=789, size=119258104, heights=225479..226267, time=2013-03-12..2013-03-17)
LoadBlockIndex(): transaction index disabled
LoadBlockIndex(): hashBestChain=00000000000002e60135b76ddd31d727f4ca44c28f142e85ff38c199b1a098e8 height=226267 date=2013-03-17 02:17:42
init message: Verifying block database integrity...
Verifying last 288 blocks at level 3
LevelDB read failure: IO error: C:\Users\username\AppData\Local\LargeDB\Bitcoin\chainstate\013292.sst: Could not create random access file.
Oh boy, this is one those "geeky" things that the masses won't understand. How did you implement this solution, in layman's terms? This is happening to me as well.