Trojan Horse leading to "Explorer caused problem in GDI.EXE"

Would really appreciate a solution to the following please:
1 - Went on website which brought up message from Norton
about a trojan horse
2 - Norton Antivirus couldn;t repair so quarantined file
3 - Did a Norton Antivirus search thing and no problems
4 - Ran Ad Aware and removed a few data miners and a data
registry which weren't there a couple of hours previously
5 - Deleted cookies and temporary internet files
on "Internet Options" in the control panel
6 - noticed my home page had been altered to blank
7 - keep getting a message saying some spyware has been
found on my computer and I need to download something to
clear it. Looks like a very dodgy message to me.
8 - Removed a couple of things I didn't recognise on
Add/Remove Programs (Both had funny codes with one
relating to Outlook and the other to Microsoft Windows).
Doing this resulted in me being asked to reboot for
changes to take effect.

Anyway, the following has resulted from the above:
1 - Explorer message appeared in a big white box saying:
"An error has occurred in your program. TO keep working
anyway......Close or Ignore"(a common message so you'll
know the rest).
2 - Clicking Ignore resulted in nothing happening so I
clicked Close
3 - Following message appears: "Explorer caused problem in
GDI.EXE". Closing this message results in blue screen.
4 - Turning PC off and then back on results in the white
boxed Explorer message. If I continuously click on ignore
then I can slowly get onto my desktop and see all icons
but can't actually use it as anything I click on results
on big white box with heading relating to what I click on
(i.e. instead of Explorer I've had MSNMGR and NMAIN).

Sorry for long message but trying to include everything
from memory. Can anyone help?