What version and distribution of Linux are you using? Does it seem to lockup on a specific page or pages? Does it lockup on pages using java?
I have netscape 4.7x lockups on occasion but, mostly on pages using java. I use Mozilla 0.9.4 as my primary browser. Works goods for the most part. Still has a few bugs. Renders pages better then netscape 4.7x. Fonts look alot nicer. I use Sun's java plugin 1.3.1 with it and it works much better on java pages then netscape. There is a slight hang (delay) sometimes when loading a page using a java applet after first starting Mozilla. Overall it works very good.