Hi again Artlav.
The intermittant starting is properly fixed, but something you enabled has broken things differently. On my laptop GRUB prints the module loading messages, then it gets as far as changing the VGA font, but the green "Mounting root" never appears, and it just sits spinning the CPU.
On my desktop it gets as far as "Mounting root" but just sits there, with the floppy drive light stuck on (even though it was booted from the floppy image in the bootable CD).
I tried it again in VirtualBox, and it seemed to all work perfectly as described.

I tested all the GUI stuff, dragging windows, the fire simulation, and so on ("typable text" not finished I assume -- has a caret but can't be edited or selected). I tested the other programs (sprite, sinw, drheap, zgl_demo, xmcd) too, and the only issue there is that the sprite stuff does not undraw itself -- it leaves old copies of the sprite behind.
I wasn't sure what all the console commands were supposed to do so I wasn't sure if they all worked. "mt" just prints an infinite number of A's and B's and X's and dashes, but the rest seemed to be sane.
Some other things you're probably aware of, but anyway:
-- Keyboard handling is weak. Layout at fixed at US (at least in the version you sent me). I have a UK keyboard -- I'd be happy to test the key map if you programmed in a command to change to a UK layout. Caps/Num lock don't have any effect. No ctrl-keys & accented letters.
-- Console's handling of some input is unhelpful: prints out tab, Esc, F-keys as little graphics; Page Up prints an 'I'. Up arrow to recall the previous command line does work, but although it adds it to the text already on the command line instead of replacing, you can only backspace through the newest added characters. Try it to see what I mean.
-- Console should have an error for invalid commands!
-- GUI needs Z-order & keyboard focus handling (I'm sure you know this perfectly well -- it just needs to be over-stated because it's important if you want a good GUI!)
-- The file system on the floppy image seems to be corrupt. If you open it in WinImage the directory structure and the dates/times on the files are missing. I don't think that's why it's not starting on my PCs because I looked at the older floppy image versions and they're the same. GRUB doesn't seem to mind.
I don't mean to nitpick -- just trying to be a thorough tester!