Wha?
We use Netscape at work, and it hangs like that all the time. The only way i can un-hang it is to clear the cache, delete the history, close Netscape and open it again.
And 4.08 is not the latest version, they are up to 6.0 now.
As much as you may not want to support Microsoft, you may want to consider switching to IE 5.5. Much quicker and more stable.