dyna mo

Anyhoo, one of my boxes is acting up and I wanted to see if you have any thoughts. Several (but not all) programs are running slow. Both browsers take forever to load pages, many times the server will time out. when I click on the file icon in the tool bar for windows explorer (the computer explorer, not the internet explorer), the window that pops up is the libraries wiindow, with all blank icons and the comp tries and tries to load that window and never does, so my favorites, library, and computer locations never show- no hard drives, no documents, music, desktop or recent places show.

In fact, the green bar going across the top never even starts. Also, I run 2 monitors on this machine, on reboot the main monitor is not found many times, i've switched cables and monitors and cannot find a pattern, then out of the blue, the computer recognizes both monitors.

Things i've done-

*updated* windows 7 from the disc. (it stated there was a .net 4.0 framework issue and it *repaired* it.
reseated the video card and updated the driver.

ran syschk from the cmd prompt (no issues found)

ran deep scan with ms security essentials. no threats found.

uninstalled and reinstalled several software apps.

ran memory check- all good.

ran *disk checker, repair bad sectors* on all drives, no bad sectors found.

replaced 2 secondary drives with one larger drive.

I think that's all i've tried, i wonder if i should f disk and reinstall everything on a completely wiped c drive? or maybe it's a hardware issue, the power supply? maybe the video card? i don't think it's the motherboard or cpu as the sytem goes through the boot sequence properly, it seems.

Any ideas? thx