Windows 7 SP1 - Slow Start Up After Power Outage

This HP computer is running Windows 7 - 64 Professional, version 6.1, build 7601 Service Pack 1. The last time I had a normal start up was last Saturday after turning off all the computers and unplugging due to thunderstorm activity in the area. Yesterday morning, Sunday, we had 4-5 momentary power outages where the electricity pretty much flickered a few times, then stayed on. This computer did start up, but the start up process took approx 20 minutes.

I restored the computer to 3 days prior with no noticeable difference, ran defrag with no noticeable difference, and ran chkdsk, which did make a difference. The 1st start after the chkdsk was a normal quick start, then subsequent starts take approx 3-4 minutes, so it has slowed down again, but not near as bad as the original problem. The start up goes as follows:

1.) The normal Blue HP start up screen for approx 20 seconds, then,
2.) The windows graphic with the changing colored "windows" on the black background, then,
3.) a completely black screen for approx 2-3 minutes with minimal flashing of the HDD light, then
4.) proceed to Welcome to Windows screen where everything loads and the HDD light is pretty much steady. Within 30-40 seconds of getting to this point the normal desktop is up, icons are loaded, and computer is ready to use.

My step 3 noted above - the black screen, is usually 15-20 seconds max, so it seems whatever the hangup is is occuring during that time. After the start up is complete everything works normally. There isn't any abnormal use of memory or CPU usage.