Okay, solved the problem. Sorry about that.
Hackedbox and IceWM, same error as above.
Changed xorg.conf from 16 bit to 24 bit colour and now flaxpdf launches. Still shows this error but launches okay:
libpng warning: iCCP: known incorrect sRGB profile
So anyone else with similar issue, run in >16 bit colour mode. By comparison, Evince does not require >16 bit colours.
FlaxPDF is nice. Opens almost instantly on old hardware. Took a bit to load 160+ page Corebook.pdf - 100% processor load for some time, single core system
- but once loaded all the pages are ready and display briskly. Refreshing change from Evince, which takes considerably longer to launch and render pages.
Curaga - Is there any way to enable continuous mode when using Page Down key. For example when using trim or full width mode, pressing Page Down key to display the next set of lines/bottom of the page rather than just skipping to the top of the next page (miss seeing the bottom half of the pages). Otherwise lots of mouse scrolling, down arrow use or having to switching to Page view where some of the pages/print can be quite small.