Windows 7 Windows 7 - Need help on start up :)

i have windows 7 64bit, and i7 processor, and a hd 5830 graphics with 3gb of triple channel ram.... the problem is that when i turn my pc on, the windows welcome screen comes on, after its done what it does, my screen goes black with the cursor showing for 5-10 seconds, then my desktop shows, ive put services on minimal and selected no startup programs, i dont understand why its doing this because on other windows 7 pc's after the welcome screen loads their desktops show straight after without any black screen delay???

I cant think of anything which ive installed which would cause this, any ideas, my cpu and so on works fine because its smooth running once its all loaded up