What is the exact product number of the Samsumg stick?
 
Are you using just the Samsung stick or are you trying to use a combination of the old and new sticks?
 
Oh, and what is the exact model of the Acer (eg: 5520-5908)?

You bought 1 single 2gb stick to replace 2x1gb sticks? Bad idea.

I was trying to run the Samsung with one gig of the old stick.
It's a Samsung M470T5663QZ3 - CE6
I believe the model is an aspire 5520 - ICW50

Any ideas?

As DosFreak suggests, installing memory in exact make, model and type pairs is the best way to go.
 
I am not sure where or how you bought the memory, but using the memory manufacturer's memory config. utility is the best way to go.
 
According to the Crucial memory site,you don't have to install in pairs, but will get you the best dual channel configuration performance results.
 
Does the new stick alone work? If so, you can buy another stick of the exact model number and you have increased your RAM.
 
 
If not, you know that your machine does not like the new RAM at all. Motherboards can be picky about RAM.
 
I saw nothing on the Acer site and their user manual and their support site is silent about what RAM to use or what has been tested to work.
 
Of course, I may not have looked deep enough at their web site.
 
Try posting on a forum where users may have experienced the same issue or that has a section dedicated to Acer laptops, such as this forum.
 
 
 

Thanks a ton!