down loads

I am looking for some info

system:  PIII-500 / 500 MRam / Win98SE / Mozilla 1.7.5 / ZAP 5.5.062.011
           AVG 7.0

problem:  Down loads do not start / stop part way along.

When this happens I have to shut down / restart the browser to even get 
to "surf again".  It seems to be browser related because, changing to 
IE, and returning to the same site enables me to get what I was looking 
for.  Last place was the site for Wall Watcher.  Three tries for 
mozilla.  No go.  One try for IE.

Perfs set:  cookies custom / image from originating site / script off 
mostly, but on for some sites (hot mail ect)

Any Ideas ??

thanks