Windows XP: Odd Slow Startup after Service Pack 2

Odd Slow Startup after Service Pack 2

After I upgraded to SP2, my computer is suffering from an very strange problem. When I start a cold boot, the machine turns and I can hear it working but nothing comes up on my monitor. If I enter my password (my screen is black), I hear the 'music' and about 7 minutes later the screen appears and all is well.
These are the unsuccessful steps I've taken to fix this so far:
1. Totally scanned the computer for viruses, spyware etc - no problems found
2. Entered msconfig and turned off services, then turned off start up etc. - no results
3. Turned off everything in startup except the must runs (boxes are always checked).
I'm at a loss.
When the computer does come up it is running perfectly the problem is totally related to startup.
j.