Turbo dead?

Hi All, hoping you may be able to help.
I was investigating an oil leak and found the EGR valve covered in oil, I'm not sure if that's where it's coming from or from the rocker cover and spraying upwards(?).

I cleaned the oil from the area, and removed the short intake pipe to see how much oil was in there (not too much)
I also removed the bottom hose from the intercooler to check the same (none).
I put it all back together, ran it, and the closed the anti shudder valve (Don't ask me why I did that, just fiddling!?), which caused the car to stall (not surprisingly!)
Now driving it there's no power.
I connected VACD Lite and found the inlet pressure isn't increasing with revs, so it looks like the turbo's not spinning!:aargh4:

I'm not sure how what I've done could have seized the turbo??
Can anyone shed any light on this??
Many thanks!

Are you sure you haven't left a vacuum pipe off?

Thanks Crasher, yes, where I pulled the vacuum lines out the way to clean the oil mess, I'd managed to disconnect one from its connection down the front of the engine!
So panic over!
I rang a mechanic friend who asked the same question!
He did also say that he thought there was an issue with the rocker cover and exhaust gas outlet connection, which causes the oil leak issue.
Is anyone familiar with this?