My Taskbar and Icons take a long time (1 ½ minutes) to appear on the desktop. This started a couple of days ago, but I have since restored the system back to well before this problem started - with no luck. I have run AVG and Stinger anti virus scans, as well as MS anti-spyware, Spybot, Adaware, Bazooka, SpywareBlaster, and RegScrubXP, but no help. When my desktop appears, I notice under Processes in Task Manager, that only about half of the 40 or so processes have started. Then – after a minute or longer the rest of the processes load. This may be normal, I don’t know. Could the processes loading sequence have changed, causing the Taskbar and Icons to load at a later time? Also listed among the processes is “Isass.exe” which has a scary ring to it. I’ll have to Google that one.

Looks like that can be a virus-
http://www.softwarepatch.com/tips/isass.html
Also try to limit whts loading at boot. you can check ur startup list here
http://castlecops.com/StartupList.html.
How much HD space/free space and RAM?If ur drive is choked or cluttered with fragments also the boot, shutdown etc can be slow. Run a disk clean up and defrag regularly.