You might try a clean boot in order to isolate the problem. Boot in Safe Mode and see if the long start happens too.
Anyway, besides the below article try to remove any external devices one by one.
Q310353 - "Q310353 How to Perform a Clean Boot in Windows XP"
Trying to unweave, unwind, unravel
And piece together the past and the future,
T. S. Eliot
I have a Dell Dimension 8200. It runs fine and has no real problems except when I try to log in as my user account. I type in my password and the screen says "loading personal setting" for about 2 min. It has never taken this long and was usually instantaneous. If anyone has any idea how to fix this, it would be greatly appreicated. I've spent about 3 weeks trying to fix this and I havent fixed it at all.