Client is freezing 1 time per a day

[VeryImportantPerson]

We develop embedded system solutions, and we run usually (Microsoft) Windows Embedded Standard 7 operating system on all our devices. Our devices usually does not have keyboard and mouse, half of the devices has no display, half of them have touch screen display.

One of our product, a xxx machine, uses Ultra VNC. We have two devices on the xxx. One of them is making the calculation, keeping the connection with the xxx, but it does not have display. The other has display, but very week CPU, memory, storage. So, the first device generates the data, the information, and the second will show it for the driver (and also prints the tickets). The first device runs the Ultra VNC server, the second one, with the display, runs the client.

The second one, with the client is freezing 1 time per a day. Not the whole device, only the Ultra VNC client. The freezing is not 100%, some functionality is still running. I got the job to investigate the issue, and fix it.

We tested with more versions of Ultra VNC, both server and client side. The symptoms are the same with all the versions. In this moment we use ultravnc 1.2.1.0. As I wrote before, that the freezing is not 100%, some functionality is still existing. The usual behavior at the freezing is:
The UVNC server is running. The UVNC client is running. The client is not showing the changes on the screen of the Client. When we touch the screen (it has touch screen) of the client, the server is reacting on this, so, it means, that the client was able to send successfully the information to the server, and the server was able to interpret this information, and forwarded the touch event to other programs running on the server side.

I would have a few question:
1. I tried to download the source code from your server. But the version numbering is different for the source code and the running application. Running application is 1.2.1.1 or 1.2.1.0 or 1.2.0.9. But the source codes uses totally different numbering, like rt1055, rt1054, rt1053. How can I know, which source code is equal to the specific numbered applications? For example I would need the source code of 1.2.1.0 application.
2. Do you know this behavior which I described before, have you ever met with these symptoms, do you know what can be the problem? (e.g. low memory or faulty Ethernet card, or some strange Windows behavior?)
3. Do you have some idea how to investigate easy and fast the problem? (e.g. some special and deep log file logging about the internal states of the Client and Server side?)
4. What softwares I exactly need to compile the UltraVNC? Visual Studio, I guess, but anything else? Any SDK? WDK? DDK? Special libraries? Which version of the Visual Studio I need? I did not recognize the “iss” extension files. What are these? Which version of Visual Studio I would need? I found .vcproj files, but no .sln files, I did not understand it.