The app fails to start properly, due to missing kernel32.dll!SetSearchPathMode API:
See full keepassx.log for details and keepassx-error.png screenshot.
According to MSDN, this function was introduced starting from Windows 7/Server 2008 R2, but is also available for XP/2K3 via update (see "Redistributable" item in "Requirements" section), so it already exists in XPSP3/2K3SP2 as well.
Also, the proof for that is, this app runs successfully there, as visible on the keepassx-xp.png screenshot.
I implemented SetSearchPathMode and RtlSetSearchPathMode, which the 1st one should call from ntdll, and after this, the app also starts successfully in ROS, as visible on keepassx-ros.png screenshot. All my changes are attached in SetSearchPathMode.patch as well (experimental). PR will be follow soon.
Tested build: 0.4.15-dev-2359-g0dedb9b.