I am a fairly seasoned and knolegeable tech but yet I am stumped at this problem with a Dell Insperion 5160 notebook with Windows XP. This notebook came to me not able to pass post, it would turn on and shut down within 15 seconds and the (Lock) (A) LED on the top panel just flashes. After pulling all memory, modem,CD etc.. the normal troubleshooting stuff, it still would not pass post and would shut down. I then disassembled the laptop and reseated the processor and cleaned and applied heatsink thermal compound and the machine still did the same. I removed the ram once again and put a 128mb chip in and it booted up. The strange thing is that the original memory in the machine was tetsted good in another machine but with this memory in the Dell 5160 it will not post and shut down. The memory is pc2700 266/333 ddr 200 pin. I put a brand new 512 chip in of the same specs and still no post. Here is the really strange part, the 128 mb module that it will boot up with is pc2100 266mhz DDR. Is this a corrupt bios issue? If it is unfortuanatly a bios flash will not take for some reason on this machine either. anybody have some ideas on this?