Suppose you have an application running and the Task Manager says it is using 40 MB of memory. You minimize the application and its memory use drops to 4 MB. You restore the application and memory use goes to 12 MB.

When you minimize an application in Windows NT and Windows 2000, the operating system swaps most of its memory out onto the hard disk so other programs can use the physical memory. When you restore it, the application begins reclaiming physical memory. Eventually it will take it all back.

Click here to see an interesting discussion about this in the DOTNET archives.