Hello experts! I posted a week ago about switching out the system board on the 4100 due to a busted usb port. I didn't get any replys on the post,not sure why.The original was a 866 mhz p3 and the replacement was a 1.13. Well I decided to just go for it and all seemed to go well. I swapped out the memory,HD,Display and keyboard.The pc started and after finding several new components it ran! I started and shut it down several times and it worked ok,locking up once on a software install.When I shut it down and got back to it after letting it sit for 8 hours or so it wont start. Upon starting now the power lights flash and there is a short flash at the bottom of the display and then you hear a slight buzz sound coming from the area of the left rear corner of the case at the bottom of the display.It made the same sound when shutting down the pc by just using the power button and not doing it the proper way.I'm at a loss here now.It ran perfect when it started originally.I did manage to get it started a couple times after this happened by once,removing the cd drive? Thinking a connector wasn't seated properly I pulled and reseated the HD,display connector and memory. Any ideas? Suggestions. Anyone have this problem before?