RW Paint ran out of memory - RealWorld forums

i have a 8GB of ram, and RW paint only using 800mb of it on my large images (3000x3000 200dpi). As i can see on my task manager, i still have 4 more GB of unused RAM, but why RW Paint said error 0f0xxx (i forgot the error number) and tell me im ran out of memory. Is there any way to fix this?