To be honest, the intelligent way of approaching this would be to find out what system resource you are low on first and then think about the solution. This is what the system tools are provided for, but there are plenty of free software packages out there which can monitor things like memory usage, and hard drive space if you'd rather use something different. Knowing what circumstances you get the message would help too. If you are running lots of tasks (programs) on a machine with only a small amount of memory, you'll be pushing resources to their limits as the system will be hitting the swap file all the time. If you get to a point where the system cannot extend the swap file due to insufficient disk space then you've got a real big problem. A full disk should show as a different message, so the best guess (in the absence of more info) is that your running more programs at once than the system has enough memory to handle. We could do with knowing what you are running and how much memory you have before we can even make a guess. Suffice to say that memory is really cheap these days and there's no excuse for running a Windows PC with less than 512 Mb. Even 1 Gb, which is plenty for most people, is quite affordable.