Recent version of WinSCP wont copy large files

Hi all,
I've been using WinSCP forever. I have the latest version of Putty, and I have a private key in my puttyagent that gives me access to all the unix/linux machines I work with.
I currently have WinSCP 5.7.2, and I have rebooted my windows 7 after installation.

Generally I use WinSCP to transfer to a Solaris Sparc machine, but recent versions of WinSCP have been telling me to turn off optimization - which I've done but the error keeps coming back. So I've tried switching to a Linux - CentOS 5, where I can update the SSH daemon.
However when I transfer a large-ish file I get "Incoming packet was garbled on decryption". I set the debug log but it doesn't give much info (see after). I set the "Ignores SSH-2 Maximum packet size" known bug to "On" but I still get the problem...

I've always sworn by WinSCP, now I'm lost! Any ideas?
Thanks, Ciaran

. 2015-04-15 10:11:47.398 Sent 32768 bytes
. 2015-04-15 10:11:47.398 There are 0 bytes remaining in the send buffer
. 2015-04-15 10:11:47.398 Looking for network events
. 2015-04-15 10:11:47.398 Detected network event
. 2015-04-15 10:11:47.398 Enumerating network events for socket 992
. 2015-04-15 10:11:47.398 Enumerated 1 network events making 1 cumulative events for socket 992
. 2015-04-15 10:11:47.398 Handling network read event on socket 992 with error 0
. 2015-04-15 10:11:47.398 Received 28 bytes (0)
. 2015-04-15 10:11:47.398 Read 4 bytes (24 pending)
. 2015-04-15 10:11:47.398 Read 24 bytes (0 pending)
< 2015-04-15 10:11:47.398 Type: SSH_FXP_STATUS, Size: 24, Number: 5466886
< 2015-04-15 10:11:47.398 65,00,53,6B,06,00,00,00,00,00,00,00,07,53,75,63,63,65,73,73,00,00,00,00,
< 2015-04-15 10:11:47.398 Status code: 0
. 2015-04-15 10:11:47.400 Session upkeep
. 2015-04-15 10:11:47.400 Looking for network events
. 2015-04-15 10:11:47.400 Detected network event
. 2015-04-15 10:11:47.400 Enumerating network events for socket 992
. 2015-04-15 10:11:47.400 Enumerated 1 network events making 1 cumulative events for socket 992
. 2015-04-15 10:11:47.400 Handling network read event on socket 992 with error 0
. 2015-04-15 10:11:47.400 Selecting events 0 for socket 992
. 2015-04-15 10:11:47.400 Incoming packet was garbled on decryption
. 2015-04-15 10:11:47.401 Connection was lost, asking what to do.
. 2015-04-15 10:11:47.401 Asking user:
. 2015-04-15 10:11:47.401 Incoming packet was garbled on decryption ()
* 2015-04-15 10:11:52.877 (ESshFatal) Incoming packet was garbled on decryption
* 2015-04-15 10:11:52.877 Copying files to remote side failed.

I copied the file to my local disk and then transferred it successfully to the CentOS system without any interruptions. Strange, but at least it has successfully arrived into my unix environment.

However the transfer to Solaris sparc still stops. I get a popup saying "Host is not communicating for more than 15 seconds, Still Waiting", with "In the problem persists try turning off 'Optimise connection buffer size'. It is already off...

Thanks for your report.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.

What version were you using previously (that did not have the problem)?