Computer Slow moving between user accounts

[#1]

Had to reinstall windows recently. Since the reinstall we have found logging on and off of different user accounts very slow - well over a minute.
Used Cont,Alt, Del to see what is running slow and the only one of high usage is 'System Idle process' which seems to take up only 16K of memory.
Running XP on 1GB of memory.

[#2]

You haven't installed an earlier version of Norton Internet Security have you 

[#3]

If you have reinstalled then there is possibly 200 updates to download even if you have SP2 this may well account for it.
Is it the same for all users or just one if you give us an idea of what you have running we may be able to pinpoint it.

[#4]

I assume all the updates are in place. A lot downloaded soon after I reinstalled.
I have also noted that if I go to Add / Remove programs, the PC will lock up. It shows the message 'populating list' and progresses no further and you can't do anything else until it is closed.
Also Adobe is not being recognized now.

[#5]

Spyware scan completed two days ago. Nothing unusual.
Reloaded windows tonight. Not sure if it is better or not.
One thing I have noted. The picture icons would not load when loading windows and all my bookmarks have the same little picture icons. Like they all have a default icon!
Any ideas

[#6]

Two picture icons.
First each account users has a picture icon beside their account name when they log on. XP has a variety available. Presently they have all defaulted to the same. Usual these icons are all different, before personalising.
Secondly when you click on favourites, or as in the case here in Firefox, bookmarks, you get a symbol (icon) next to the favourite name.  A number of these have used the same icon when they usually have a different on.
How to I check the system log?

[#7]

On Event viewer/ system all the errors I have looked at have the following description The device, \Device\Harddisk0\D, has a bad block. 39 occurances on start up this morning. Help on this issue states I should replace the hard disk! Time to go shopping?

[#8]

Ran Disk Check and fix and left if running while I went out. Still running when I came home four hours later. Seemed to get stuck in the point - same text kept reappearing.  Not a good sign I suspect.

[#9]

It certainly sound poorly. Its down to money really a new HD is the best answer. Other than that you can get software like spinrite which will low level format the drive and may fix it.
The other idea is to work out were the fault is and make a partition that doesnt use the bad bit so if its right at the front you could move the partition to just under 2 gigs and you may get away wit hit for years. Same if its at the end leave it blank and stop the partition before the bad bit.
Chances are if its got bad bits its not going to last. How old is the drive as lots of drives have a 2 year or more guarantee worth check the website to see if it can be replaced free