I can't see anything special about block 575176. Can you post the output of 'getpeerinfo' in the debug console?
Can you also see if block 575176 matches the network?
> getblockhash 575176
bfa0df972c20708e5e275812ecdfc6c16ec79c9e51ea5497a6191d9e2be18e1b
have you a new version?
[
{
"addr" : "85.17.81.169:12344",
"services" : "00000001",
"lastsend" : 1420139171,
"lastrecv" : 1420139171,
"conntime" : 1420138441,
"version" : 60006,
"subver" : "/Satoshi:1.3.1/",
"inbound" : false,
"releasetime" : 0,
"startingheight" : 661459,
"banscore" : 0
},
{
"addr" : "107.170.49.232:12344",
"services" : "00000001",
"lastsend" : 1420139234,
"lastrecv" : 1420139234,
"conntime" : 1420138463,
"version" : 60006,
"subver" : "/Satoshi:1.3.1/",
"inbound" : false,
"releasetime" : 0,
"startingheight" : 661462,
"banscore" : 0
},
{
"addr" : "106.186.25.224:12344",
"services" : "00000001",
"lastsend" : 1420139194,
"lastrecv" : 1420139077,
"conntime" : 1420138464,
"version" : 60006,
"subver" : "/Satoshi:1.3.0/",
"inbound" : false,
"releasetime" : 0,
"startingheight" : 661463,
"banscore" : 0
},
{
"addr" : "203.20.114.252:12344",
"services" : "00000001",
"lastsend" : 1420139162,
"lastrecv" : 1420139171,
"conntime" : 1420138465,
"version" : 60006,
"subver" : "/Satoshi:1.4.0/",
"inbound" : false,
"releasetime" : 0,
"startingheight" : 661462,
"banscore" : 0