Hi, My Dad is having some problems with his iMac. Specs as below: Model Name: iMac Model Identifier: iMac6,1 Processor Name: Intel Core 2 Duo Processor Speed: 2.16 GHz Number Of Processors: 1 Total Number Of Cores: 2 L2 Cache (per processor): 4 MB Memory: 1 GB Bus Speed: 667 MHz Boot ROM Version: IM61.0093.B07 SMC Version: 1.10f2 Serial Number: W863702QVGN NVIDIA GeForce 7300 GT: Chipset Model: NVIDIA GeForce 7300 GT Type: Display Bus: PCIe PCIe Lane Width: x16 VRAM (Total): 128 MB Vendor: NVIDIA (0x10de) Device ID: 0x0395 Revision ID: 0x00a1 ROM Revision: 3021 Displays: iMac: Display Type: LCD Resolution: 1920 x 1200 Depth: 32-bit Color Built-In: Yes Core Image: Hardware Accelerated Main Display: Yes Mirror: Off Online: Yes Quartz Extreme: Supported Display Connector: Status: No display connected When he is using the internet he is experiencing some bizarre things! The screen begins to get dark, starting at the top of the screen and moving down the screen like a roller blind, until the whole screen has darkened - you can still see the desktop image underneath - its a bit like when you select the Dashboard, only darker. Then a message pops up, much brighter than the darkened background. The message says, "You need to restart your computer. Hold down the power button for several seconds or press the Restart button" The rest of the message box is obscured by what I would describe as colourful TV interference. Like an untuned TV picture. If left, the iMac goes to sleep, but won't awaken. It just locks up. The usual sleep LED on the front of the mac, which usually blinks, is not lit up at all. I've attached a screen shot to show what I mean. The actual screen is darker than it looks in this image - I think the flash has caused it to look brighter here, but hopefully you get the idea! Cheers. Any ideas VERY welcome please!! Thanks in anticipation. PS: apparently this doesn't happen at all if my Dad is not using the internet at the time, and it also started after he had posted up a message on a boat classified ad website.