Question: Big Big Integral Problem

I got a big problem with one kind of integral function. Now, I am using Maple 8 or Maple 11 to get some results from my research topic. However, when I took three times integral like :

f:= Int(exp(-t^2),t = 0 .. infinity)+Int(Int(2*Int(.1*exp(-.25*(u-s-k)^2)*exp(-(-.5*u-.5*s-.5*k+t)^2)*exp(.25*(u-s-k)^2)*exp(-.1*k),k = 0 .. u-s)*exp(-u^2)*u,u = s .. t),t = 0 .. infinity);

After that, I try to draw the grahp of the above equation.

plot(f,s=0..1);

Before I simplified the above function, I got the message : "Execution stoppted: memory allocation failed" after 3 hours running...oh...god

After finding out the way to simplify before taking integral, I applied it. Even though the running time decreased dramatically (about 4 mins), I still got the error message about mserver.exe,the program stopped and the Visual Just-In-Time Debugger of Microsoft Visual Studio 2005 appeared and I couldn't receive the outcome.

I don't know what it's going on. I tried to use more powerful computer with 4GB RAM. But it seems that everything is not getting better.

I need your help. Thanks for advance.