WOW! i found someone with the same problem as me! I have a Sony CPD-g420s (Same monitor just the 19 version)
I recently moved and the First thing i noticed is a slight discoloration in the lower left corner of the screen, It looked like a magnet was nearby. However no matter where i put the monitor i recieved this distortion (funny if i lean the monitor forward it becomes worse) Within a day of moving the monitor did this "cracking" sound that we've talking about. Nothing happened because of it and i didnt think much of it.
One moring about 2 weeks later while my step dad was outside hedging the bushes with an electronic hedger (relevent? i dunno the outlet is on the same cricut as my room) My moniter clicked again, twice in about 10 seconds. After this the picture became slighty blurry. I turrned it off and waited till he finished outside. I tried again about 2 hours later and the picture was fine. But 10 mins later it clicked and went completly blurry.
This is how its been for days. I can let my monitor cool off and when i turn it back on the picture is fine....5 mins later or sometimes more sometimes less it swtiches to being completly blurry again, without and cracking sound. Ive tried other computers, other outlets just about Everything i can think of and nothing seem to change it from going blurry, it will even do it without having a signal going to the monitor, the "no signal" sign just goes blurry.
If anyone has any new information about what could be causing this i'd love to hear from you. I do plan on sending it to a tech repair center on thursday but its going to cost me 125$ as a flat rate....and i only paid 225$ for it!