I have a client with a Compaq Presario SR1135CL running Windows XP SP2. The computer freezes intermittenly but I have been able to recreate it to the point where it appears to happen when on email or the internet while connected wirelessly. It does not seem to happen (or I can't recreate it) when plugged into the internet with an ethernet cable.
I did a complete system recovery with the Compaq System Recovery tool.
I bought a new Linksys USB wireless adapter (the old one was a Zyxel), installed it and was able to immediately recreate the problem.
The computer does NOT seem to freeze if plugged into the internet with ethernet cable. It only appears freezes when connected wirelessly with the USB adapter.
I have run the hardware diagnostics that came with the HP computer. They all passed.