This is aimed at Premiere Pro, but may help
A link with many ideas about computer setup http://forums.adobe.com/thread/436215?tstart=0
Many of the ideas at the next link are generic enough they have helped some Non-Premiere users fix problems
Work through all of the steps (ideas) listed at http://ppro.wikia.com/wiki/Troubleshooting
If your problem isn't fixed after you follow all of the steps, report back with the DETAILS asked for in the questions at the end of the troubleshooting link
I have been using this premiere for well over a year without problems.
If it has worked perfectly for a year then something else must have changed. Perhaps a video card driver (if you have Nvidia then read the many forum posts) or a new camcorder with a different video output.
You say that you have all the latest updates. Does this mean that after you reinstalled windows you then updated windows and all drivers? If so then, if the fault is driver related, you will have reinstalled the offending driver. You may have to reinstall windows and then install PRE4 next - before updating windowss and drivers. If that works, you should perform updates one at a time to see which is bringing down PRE.
The other possibility is that maybe your hardware is developing a fault e.g. memory.
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