Depending on what your loops is doing, this can cause your script to continue to output the same information over and over again (continuing to make the page longer and longer and longer) or it can keep processing the same information over and over without outputting anything giving it the appearance of a page that is trying to load but is lagging.
One way to help you spot this is to echo () the current counter number (or other useful information) at the beginning of each cycle. This way you might get a better idea of where the loop is tripping up.
If you're not using loops, you may want to double check that any HTML or JAVA you are using on your page isn't causing the problem, and that any included pages are without error.
If your page is blank, you may also find help in this FAQ.