More recently introduced terms such as 'annually laminated' are synonymous with varve. Of the many rhythmites in the geological record, varves are one of the most important and illuminating in studies of past climate change. Varves are amongst the smallest-scale events recognised in stratigraphy.
PCs are designed to shut down automatically when heat endangers the hardware. To find out if this is your problem, download and install Speedfan. It's small and free. Although Speedfan's basic job is controlling the speed of your PC's fans (you probably guessed that by the name), it also provides the CPU temperature.
You know, when your computer completely freezes up and the only thing left to do is to resort to shutting off your computer at the switch and turning it back on. Lots of things wrong with doing that, even if the consequences are not as bad in Windows XP or Windows Vista as they were in Windows 95, 98 or ME.ven with Windows XP, Windows Vista, or Windows 7, shutting your computer off at the switch and then turning it back on should be done only when you have no other option. Some bad things can happen although seldom does it result in catastrophe.