Could be a G-Force Issue if you have one. Anything beyond the limit is ignored.
I have one in my A2000 with max 16Mb, Must remove 4Mb to make all stuff work. Graphics and audio cards won't work correctly and many errors.
That makes no sense, Unless:
You are mapping fast ram into zorro2 space that other cards need,in which case this is terrible use of a accelerator and slows everything down and causes the problems you mentioned. set the jumpers to map the ram as 32 bit.
or you have some bad ram that is causing troubles,but i would bet on the above being the trouble.
in anycase this is not a normal thing for a gforce in the a2000.