Sarakat: That does sound like a heat issue. However, before you start tearing into your notebook, be advised that nigh onto =all= of them have no fans in them. Fans are high maintenance items, they consume vital space, they create even more heat, and there frankly isn't enough room in any notebook for any fan that could be mounted in them to actually get an airflow going. They use passive cooling methods; the backplate is one huge heat spreader, there is convective cooling or both. The best way to check is to prop your notebook up by the corners, so that the bottom is at least an inch above any surface. Then place a fan so that it blows air parallel to the screen, and beneath the body. Load Poser and strain the bugger. If it handles it, then you have your answer. All you would need to do then is make sure that either there is something that dissipates heat to set the notebook on, or keep the envrionment a few degrees cooler. For that matter, it would be simple to build a small stand and baby fan arrangement (say one of those clip on types. Definitely enough CFM for this job)to prevent the issue. And actually, smiller1, it does. Assuming that the drive in question is an IDE drive, and one of the ones with a decent spindle speed, a seriously fragmented application can cause almost continuous accessing of the drive. That will drive up the heat, and if the controller electronics on the drive are dicey to begin with, you get thermal errors. As there is no pattern to what files get fragmented, save what other programs are doing, and the order in which you are running them, then its easy to see how the problem jumps from app to app. One instance it might be Poser that fragmented enough to push the spindle heat up to where the controller chip started barfing at you. Let it cool, defrag, and it might be Photoshop that gets scatters all over creation the next go around. One of the points that keeps getting missed in any talk about thermal issues is that modern IDE devices have their own controller and I/O electronics on the actual drive. And irregardless of their cable configuration, they almost inevitably wind up in an area where the air doesn't move, or in the case of the really cheapo baby towers, in a mounting frame directly under the power supply. And the problem is a royal bitch to isolate because it is dependant on a transient thermal condition.