System takes several minutes to respond normally after loading desktop
I'm running Win7 x64 on a 1-month old i7-970 system with 12 GB RAM. The OS and apps are on an SSD while my data are on a 2-disk RAID 1. Everything was working normally until two or three days ago. Now, whenever I boot, the boot goes normally until the desktop loads. Then, while I can click on apps to start them, they don't respond for 3 - 5 minutes, and then are barely responsive once they're running, for another 3 - 5 minutes, after which everything suddenly starts behaving normally. During this pokey time my CPU monitors indicate very little CPU activity (< 15% on one core). If I try to run task manager to see what might be causing the problem, it's as slow as everything else, taking several minutes to load and then not displaying any processes. In fact, I know the system is "stable" when the processes appear in it. I've done a system restore to a 1-week-old restore point (from before this behavior appeared), but it didn't fix it.
The behavior started after (though not immediately after, maybe two or three boots after) updating my display driver (Nvidia Quadro 4000). I rolled back the driver to the previous version, but the problem remains.
Has anyone else had this problem? Any suggestions? Thanks.