@Dev
As I said before, these is a problem in the wallet. I found the bug - there is a small difference in calculating the DGW2 for some blocks, between the 32bit and the 64bit clients.
Currently there is difference for blocks 246,640,1656:
2014-04-22 08:58:46 AcceptBlock: n1=3.73083735560677665077378151181619614362716674804688 n2=3.73054699773302633758476076764054596424102783203125
2014-04-22 08:58:46 SetBestChain: new best=000000001ad15d3364a0b682a5013cda407f5fc4010c81b4ca7b825174c01e50 height=246 log2_work=41.068831 tx=262 date=2014-04-20 20:18:52 progress=0.064012
2014-04-22 08:58:48 AcceptBlock: n1=3.50214226743221201942901643633376806974411010742188 n2=3.50184475041391030103454795607831329107284545898438
2014-04-22 08:58:48 SetBestChain: new best=0000000047db5c677986af44640cd6738113780088776f4610a640e35783d183 height=640 log2_work=42.870632 tx=700 date=2014-04-21 06:09:18 progress=0.200145
2014-04-22 08:59:57 AcceptBlock: n1=1.74606346415154667361946394521510228514671325683594 n2=1.74592391304347827052367847500136122107505798339844
2014-04-22 08:59:57 SetBestChain: new best=000000006d076c7504b3e94368fb6b4920160e1958175ea588f66abe178525ed height=1656 log2_work=44.354248 tx=1958 date=2014-04-22 07:42:48 progress=0.935948
I made a quick temporary fix and tested it on 32bit linux and it is working. Not tested on windows and mac wallets, but should work.
Here is the patch:
https://github.com/ljudoed/diffucultycoin/commit/91271fa645f51bd971928c6554e5c25a8c3a9ff2