Screen won't show anything on my droid when I slide my key board in/out

[iyuzhulan]

I just got a droid from ebay several week ago. Before I root the phone it has a lag when I slide my keyboard in/out. The Screen just won't show anything, I still be able to pull the manual bar down though. After a few secs, everything back to nornmal. (after rooted the phone, it still does the same! even I overclock the phone to 1.1 Ghz) any thoughts?
Thank you