I have just installed DAVID 3.5 on several computers. Some new and some not so new.
On a current win7 (64 bit) computer there were no perceived issues.
On older Windows XP computers there were a variety of issues which included failure of the installer (double instances and total halts) , unhandled exceptions on startup of DAVID3 with reports of syntax failures in XAML. All of the issues on the XP computers were resolved by ensuring that they were up to date (SP3) and had . NET framework at the appropriate level (3.5+) with all the available fixes installed.
It is not difficult to check the state of a target computer as part of the installation process and then to stop the installation if it fails to meet the base criteria. This will remove a whole category of reported problems with the software.
I do appreciate that XP is now ancient, however there are millions of XP machines in the wild which have a new future as DAVID scanner engines
A further point, perhaps already reported: If the camera is disconnected during a scanning session then I observed an unhandled exception causing an exception loop which I could only resolve by terminating the process from task manager.