Lagged Out Computer Errors / No Access

i was just about to start up a game call EverQuest 2, whats besides the point, my mouse started lagging around, and my system became VERY slow, so i decided to restart my computer.My computer started up as normal, then when Windows XP started up (where the little bar goes across the screen to show the progress) became stop and go, in which it usually takes 15-30 seconds to start up, too 15-30 minutes! now when my computer started it was rather slow, but once a message popped up, the speed fine. The Message was the following"Failure to run NvCpl.dll Error performing inpage operation".It seemed to do be the library of my NVidia drivers. so i popped in the disks and reinstalled everything, now when i start up my comp, i dont get the error message, but my computer still takes forever to startup, i also, through all of this, can't open and folder, play any media file, get into my computer or control panel, or ANYTHING, pretty much what i can open is internet explorer, mozzilla firefox, and Run CommandsIt is a bit odd, because since i have EverQuest 2 on schedualed tasks it open when i log on, but it opens and doesn't proceed (it first scans file for the launcher incase of a change in coding or graphics, then loads up the launcher) but it doesn't proceed at all, i can download items, and i pretty sure i will be able.