This is an issue we *occasionally* see (I've seen it on one of our test systems here - although not for some time now), but isn't reproducible enough to really get a good handle on what's happening. We've done a number of things with Ping Plotter to get around it, but it seems like it has something to do with Windows and its network stack.

We've seen this mostly when a connection goes down completely (ie: all hops stop responding because of a problem in the local device). Is this what you're seeing?

What operating system are you using?