Soldat was running fine for a while.. but since the beginning of this week, it started to crash randomly. No "illegal operation" or "error number X" just crashes and returns to windows... so yeah, pretty annoying :p

Have you tried running it in Windowed mode? Also, do you have any extra programs running that you can close?

Most likely you ran out of Virtual Memory, go into your system settings and let Windows manage your Virtual Memory, otherwise, like Lapis said, close background processes. :)