First run:

1. Old files removed and new archive extracted to Bitcoin install directory.
2. Bitcoin-Qt started and synced to network, then it stucked for a while showing progress meter and acting like some blocks are missing.
3. After a while it returned to normal state, with green check mark showing sync is complete.

Debug log reveals not everything is right - an example of errors encountered, there might be more so check log file linked bellow:

2013-05-12 14:32:42 received block 00000000000000a1acafe3cb63099b5cc8b5d81a0bbbf6191f5978ea05c4372c
2013-05-12 14:32:42 Committing 30380 changed transactions to coin database...
2013-05-12 14:32:42

EXCEPTION: St9bad_alloc
std::bad_alloc
C:\Program Files\Bitcoin\bitcoin-qt.exe in ProcessMessages()

2013-05-12 14:32:42 ProcessMessage(block, 442684 bytes) FAILED

2013-05-12 14:36:03 ERROR: Non-canonical signature: S value excessively padded
2013-05-12 14:36:03 ERROR: CScriptCheck() : c33bbdb11c757e9dc38063367cb460cf47d8934f8d9600c061d989b47ef2aa18 VerifySignature failed
2013-05-12 14:36:03 ERROR: CTxMemPool::accept() : ConnectInputs failed c33bbdb11c757e9dc38063367cb460cf47d8934f8d9600c061d989b47ef2aa18
2013-05-12 14:36:03 Misbehaving: 194.213.5.15:8333 (0 -> 0)

2013-05-12 14:30:03 ERROR: Non-canonical signature: R value excessively padded
2013-05-12 14:30:03 ERROR: CScriptCheck() : e390b43b53d5aa15a6c76020b019eec470567a607d8de08153cd8882067d7a77 VerifySignature failed
2013-05-12 14:30:03 ERROR: CTxMemPool::accept() : ConnectInputs failed e390b43b53d5aa15a6c76020b019eec470567a607d8de08153cd8882067d7a77
2013-05-12 14:30:03 Misbehaving: 77.249.178.204:8333 (10 -> 10)

2013-05-12 14:31:10 ERROR: Non-canonical signature: S value negative
2013-05-12 14:31:10 ERROR: CScriptCheck() : 1958ae3b25018b63683652f9875d1655990b5e99d22753503a00d67d56a019af VerifySignature failed
2013-05-12 14:31:10 ERROR: CTxMemPool::accept() : ConnectInputs failed 1958ae3b25018b63683652f9875d1655990b5e99d22753503a00d67d56a019af
2013-05-12 14:31:10 Misbehaving: 72.48.65.87:8333 (0 -> 0)

2013-05-12 14:33:05 ERROR: Non-canonical signature: R value negative
2013-05-12 14:33:05 ERROR: CScriptCheck() : 6618eea519e01f392c48d004d81ddaea799f36ea25a6b36ed818ef021d16884c VerifySignature failed
2013-05-12 14:33:05 ERROR: CTxMemPool::accept() : ConnectInputs failed 6618eea519e01f392c48d004d81ddaea799f36ea25a6b36ed818ef021d16884c
2013-05-12 14:33:05 Misbehaving: 109.190.65.235:8333 (0 -> 0)

Client seemed to be totally ignoring new blocks added to blockchain. I have compared block height with blockchain.info and saw that my client is 7 blocks behind but still showing green check mark. Upon exit, it crashed with error as shown on the linked image:

http://i.imgur.com/yolpQq7.png
Full debug log for first run: http://www.filedropper.com/debug1

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Second run:

1. Bitcoin-Qt started and synced properly, it updated to block height 235,845
2. Everything looked normal until I checked log file. One node was spamming my client with ton of orphan stuff, address adds and spent inputs without ever getting even banscore 10. I find that hillarious. Here is snapshot of spamming, for more check debug log linked bellow:

2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)
2013-05-12 14:56:08 ERROR: CTxMemPool::accept() : inputs already spent
2013-05-12 14:56:08 Misbehaving: 85.17.239.32:8333 (0 -> 0)

2013-05-12 15:01:13 Added 1 addresses from 85.17.239.32: 350 tried, 14092 new
2013-05-12 15:01:14 Added 1 addresses from 85.17.239.32: 350 tried, 14092 new
2013-05-12 15:01:15 Added 1 addresses from 85.17.239.32: 350 tried, 14092 new
2013-05-12 15:01:15 Added 1 addresses from 85.17.239.32: 350 tried, 14092 new

Bitcoin-Qt again refused to sync with newer block which was shown on blockchain.info but it exited without any error.

http://i.imgur.com/5vRYWkh.png (note BTC Guild self-owning, sort of :o)))
Full debug log for second run: http://www.filedropper.com/debug2

Reverting to 0.8.1 for now. Let me know if you want me to test something specific.

P.S. Crashes on my machine are exclussive to Bitcoin. Beside it, I have Litecoin, Terracoin, Freicon, Feathercoin, BitBar, Small Change, YACoin, Bytecoin and PPCoin clients and none of them ever crashed. Machine has 2GB RAM and 8GB fixed swap file.

Bitcoin-Qt reverted back to 0.8.1 and started, it was in "attempting to sync" mode for few minutes and then it crashed with error as shown on screenshot bellow. I'm occassionaly seeing the same or similar errors for 6+ months now, just with Bitcoin-Qt, and so far none of MS Visual C++ runtime libraries available online fixed the issue.

http://i.imgur.com/9mFgSdY.png
Full debug log, some weird errors inside: http://www.filedropper.com/debug3

On subsequent run Bitcoin-Qt 0.8.1 synced properly and so far everything seems normal except occassional spamming by few nodes. Syncing with newer blocks works perfectly. I'll update this post if something unexpected happens.