I have an older Sony Vaio laptop that only had 128 RAM from the factory. Unfortunately, there was only room to add an additional 128 RAM which I did today. I shut down my computer, removed the battery and un-plugged it. Removed the access panel on the back of the laptop, attached a grounding strap to myself (no need for any static problems for this guy) and removed the new module from it's package. Held it at a slight angle, lined up the slots and fully seated the module...Goin great so far...Put cover back on, re-installed the battery, re-plugged computer back in and powered up....That's when the problem started...Upon start-up I got a screen stating that System32\DRIVER\pci.sys was either missing or corrupt and to insert XP CD and restart to recover using "R" at prompt. I then attempted to do this...Upon reaching the windows set-up window it would start and after a short time it would reach an error (it was either a 4 or a 7 I can't remember for sure) and press any key to escape...Did this approximately 3 times before giving up. It would not let me start up in safe mode/command prompt. At this point, I'm thinking that possibly something is wrong with the new module (Why should memory be asking for drivers?) so it removed it using the same steps as above. I then rebooted and windows came up normally...WTF?

Being of Scot/Irish/German descent I can be a little stubborn and was not willing to give up on it yet...I re-inserted my XP CD and explored it for the file missing...found it in the i386 folder of windows and copied it from the CD to my computer. I then shut down the laptop and re-installed the module...I then restarted the computer...I guess that this worked because Windows opened up normally (except much faster) and I made it back here...

My question is why would adding memory be concerned with drivers? I have adde memory modules before to other computers and never had this type of problem before...Any ideas?

Are you sure your buying the right speed/ as the laptop? (I'm assuming that since you can fit it in, the number of slots work) RAMs comes in different speeds DDR2-800, DDR-667, etc. Be sure to buy the right DDR/SDRAM and make sure the speed of the new ram is close to the current speed of your computer.

heh oops

It could have been something as simple that the module wasn't fully seated the first time.

As for the battery, I suspect that there was some confusion about this being a laptop with a battery for the power supply and a CMOS battery.

I think that you are probably correct about it not being fully seated the first time. I did a little investigation about the driver in question and it refers to "NT Plug and Play PCI Enumerater"...Makes some kind of sense if the module isn't fully seated that it may cause some kind of issue...OR the driver in question was just corrupt...We all know that this kind of stuff is common with Windows...

As far as the question of making sure that the new module was of the same type as the other one (I assume that you are talking about matching), I did that because I contacted Sony and followed their recommendation on the type of module to install along with their instructions for installing it so that is pretty much a moot point...A valid point, but moot in my case...

The best part is that everything is working well...This computer has never been more responsive since I can remember...Don't know why I didn't install the other 128mb module years ago....

Glad to hear that you got it up to speed, it sure makes it a lot more fun to use.