Windows 7 Freezes On Three Different Brand New Computers

Over the past couple of weeks, I have purchased three different computers. Two from HP and one from Dell. All three computers have the same freezing issue, even if there are no programs running. The only programs that have been installed are Quicken 2010, Turbotax 2010, and Microsoft Office 2007. The only other change made was uninstalling Norton AV and installing eset.The computer freezes up and the only way to get it working again is to hit ctrl alt delete to bring up the task manager. If I bring it up, everything starts working again for a short time. All three computers freeze often even when they have just booted up. All of the computers have been plugged into a power strip which is shared by a bunch of devices, so it's possbile that it could be a power issue, or maybe it's a compatibility issue between Windows 7 and one of the aforementioned programs.