Powerbook G4 + External Monitor + Firefox = freeze?

got a strange problem here. I posted this over at macaddict a while back, but never got a response, I'm someone can help me out.
I've got an old 20 inch blue and white CRT monitor connected to my last rev. Powerbook G4 with RAM upped to 1.5 gigs. I also have some peripherals connected to the usb hub on the monitor and all my ports on the powerbook itself are used up as well. Basically I'm running this mainly as a desktop.
So, through the day while i'm working I get these blips on the screen randomly. they are horizontal blips almost as if I've just turned the monitor on. It is seriously about a millisecond. blink of an eye. anyways the freeze happens 99% of the time right after one of these blips AND while I'm holding the mouse button (usually manually scrolling in Firefox) it freezes for a second, i get the spinning beachball, but then it turns back to the arrow. i can move the arrow all over the place, but i cannot do anything else. option+apple+esc doesn't do anything. the scaling effect doesn't work on the dock. i can't start or quit anything. if iTunes is playing, the music plays on, yet everything else is still frozen. so I open the lid and hold down the powerbutton until it shuts down. then i start up again.
i have no problems when i use the powerbook without the external monitor. so is the monitor the culprit? Do i need to get a newer monitor? could it be a problem with usb 1.0 ports on the monitor and the usb 2.0 ports on the powerbook - a conflict of interest so to speak? any suggestions?

thanks in advance!

thanks for the reply pianoman.
I have the USB cable from the monitor plugged into one of the USB ports on the PB. All four USB ports on the monitor are taken up by a scanner, printer, compactflash reader and wacom tablet (though this was happening before I had the reader and tablet connected) The other USB port on the PB is taken up by my keyboard/mouse. also i'm daisy-chaining two firewire hardrives which take up the firewire on the PB.

Yes, it does occur with Safari. It never happens with any other application. I run the entire Adobe CS 1, Quark and other various apps and it never happens with them. I work at home so I leave Mail open all the time, but it never has happened with Mail.

I'm in the market for a 22" widescreen LCD so maybe I should just go ahead and get one and see if it clears this up. What do you think?

excellent news! that seemed to be the problem. i just bought a brand new 22" widescreen AOC LCD from Office Depot and there are no blips and no freezes. I've been on it all day. i just held the mouse button on the scroll bar for a LONG time too and no freezes. i just plugged all my peripherals in a dedicated USB hub. yay! Plus I finally have this beautiful, space saving, big screen real estate monitor!
*opens multiple windows and scatters palettes all across the screen..