Drawing FBO with OpenGL on computer hungs

I have two computers, a Toshiba laptop with an i5 and ATI Radeon HD 5145, and an old Dell desktop, with Pentium D and ATI Radeon X1300 Series.

I have created a Java application, using LWJGL, that creates an FBO. The texture attached to the FBO is the size of the screen (1366x768 on the Toshiba and 1024x768 on the Dell).

I try the same application on both computers, using a program called MSI Afterburner to see the CPU usage, GPU usage and framerate.

On the Toshiba, it works perfect, on the Dell it hungs. I explain better later on.

Below is the code for creating the FBO:

//Create FBO
DisplayMode display = Display.getDisplayMode();

int fboWidth  = display.getWidth();
int fboHeight = display.getHeight();

int fboTextureID = glGenTextures();
int fboID = glGenFramebuffersEXT(); 

glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fboID);

glBindTexture(GL_TEXTURE_2D, fboTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, fboWidth, fboHeight, 0, GL_RGBA, GL_INT, 
(java.nio.IntBuffer) null);

glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
GL_TEXTURE_2D, fboTextureID, 0);

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
glBindTexture(GL_TEXTURE_2D, 0);

This is the while loop where the FBO is displayed:

while(true)
{
    renderFBO();

    glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, fboTextureID);
    glBegin(GL_QUADS);

    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

    int x=0; int y=0; //FBO position
    int w=fboWidth; int h=fboHeight; //FBO size

    glTexCoord2f(0, 1);
    glVertex2f(x, y); 
    glTexCoord2f(1, 1);
    glVertex2f(x+w, y);
    glTexCoord2f(1, 0);
    glVertex2f(x+w, y+h);
    glTexCoord2f(0, 0);
    glVertex2f(x, y+h);

    glEnd();
    glBindTexture(GL_TEXTURE_2D, 0);

    glDisable(GL_TEXTURE_2D);
    Display.update(); //Update the screen
    Display.sync(60); //Cap the framerate to 60fps
}

This method draws some textures to the FBO offscreen

private void renderFBO()
    {
        glClearColor(1.0f, 1.0f, 1.0f, 0.0f);

        //Start FBO drawing
        glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fboID );
        glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
        glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        //Here I draw some textures using quads

        //Stop FBO drawing
        glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0);
        glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    }

As I said before, the application on the Toshiba with the Radeon HD works perfect. 5% CPU usage, 20% GPU usage and 60fps.

When executing this application on the old Dell with the Radeon X1300 the computer hungs; the CPU usage is 50%, the GPU can't be measured and the fps is 0.

If I don't draw the FBO, just render it offscreen, then the old Dell doesn't hung, and I get normal results 5% CPU usage, 20% GPU usage and 60fps.

It's drawing the FBO in the quad what causes the computer to hung. And I ask, why? Why does this happen? Is there something wrong with my code? At first I thought it was the computer just being too old (it's from 2006) and having trouble dealing with FBO's, but then why doesn't it hung when rendering the FBO offscreen?

PROBLEM SOLVED

Finally got it working on the old Dell. I had to use a power of 2 texture. The ATI HD can handle non-power of 2 textures apparently, so I can attach a 1366x768 texture size to the FBO. However, I can't attach a 1024x768 texture with the ATI X1300. Using a 1024x1024 texture I get the application working at 60fps and little cpu usage.