Sorry about thee lack of info. It was late and I was tired.
Gigabyte GA-F2A75M-DD3H motherboard
AMD A8 5600K Quad core CPU
Nvidia GEForce 8400 GS 512MB
PCLinuxOS PAE Kernel (fully updated) uname -a=(3.2.18-pclos2.pae)
I just created a new Firefox user and the problem still exists. Again, this happens no matter what Mozilla product I start. And, ONLY Mozilla programs.
I have gkrellm and I start 'system monitor', so I can see constant movement on the desktop. When I start up any Mozilla program, both monitoring programs freeze for a short time until the program actually starts up.
I can't figure out what Mozilla programs are doing during that short period of time. As I mentioned, the disk lite is not on until just before the program UI is just about to be shown. Those programs seem to take a little longer to load than I remember. The delay happens on each start. i.e. after starting one instance, the delay happens when I start another instance.
Nothing show up in any logs that I can find.
After a lot of searching, it seem that quite a few other people have had this same problem, only with Mozilla applications. It turns out to be the Nvidia drivers. The new drivers are not compatible with older cards, such as mine (the 8400 GS doesn't seen that old). I switched to older driver and things are back to normal. Desktop doesn't freeze and the disk starts making noise as soon as I click on any Mozilla application. I find that very funny.