Question 1:
invoke CreateFile,...
mov [hFileR],eax
invoke CreateFileMapping,...
mov [hFileM],eax

In the code above, if I did not close it with
invoke CloseHandle,[hFileR]
invoke CloseHandle,[hFileM]
will it cause a memory leak on a windows 9x?

Question 2: Is it true that memory leaks like this will not happen on
a Windows 2000/XP system?

Question 3: What if a program hangs, will that cause memory leaks?

the memory leak comes from the fact you have an open handle in memory and you have not closed it, i have had memory leaks on winxp because of unclosed handles to CreateToolhelp32Snapshot, so i assume it is required on xp, i can't see why it wouldn't be on 9x, but i have no current 9x os running that i could test on

It should cause a memory on win9x....win9x is notorious for its handling of memory leaks - that's why I always needed to reboot so often .
In WinXP the memory leak will still occur but you can get away with it because winxp handles things safer so at most you close the app and everything is back to normal. (almost, hopefully )
But I'm not suggesting you to remove CloseHandle because if you don't weird things can happen. So it is a REQUIREMENT

If a program hangs there is a possibility there will be memory leaks......but why would you want your program to hang ?