Memory tests bad but works fine?

I have an acer aspire one nav50

this computer had 1gb of ram so i figured id upgrade it to 2 gb ( only has 1 slot).

I never had a BSOD , but when i tested the 1gb of ram with memtest it failed and found lots of errors. Even with that in mind i never ran accross problems with it.

So i buy a ( 2gb ) stick to sort of improve the overall function of the laptop, i install it and load it up windows , bios reads it fine with no issues. Out of curiosity i run memtest to see if this one won't run across any errors.

45% through the test and then it too gets errors, which is odd because this seems to work otherwise without issues.

I am using pc2-6400s-666 memory on the laptop

 

Give Memtest86+ a try and see if it finds any errors.

http://www.majorgeeks.com/files/details/memtest86_ffaa.html

 

I already ran memtest as per my initial post , the most recent version won't work for my motherboard so it uses an older one.

Like i stated even when i had the 1gb in there i never ran across problems other than it being occasionally sluggish due to my having multiple things open.

Ive had this for 1.5 years, i bought this second hand USED so i don't know what memory stick it original came with. It already had a pc2-6400s when i bought it and even though it tested bad through memtest i have yet to ever get a BSOD or any errors.

Crucial shows i can use either pc2-5300 or pc2-6400, my laptop model also appears to be acer aspire one 532H as i couldn't find much with ''nav50'' even though that's is the model number written below the laptop.

Since the recent 2gb stick i got also tested bad ( according to memtest) but yet i can still use it just fine without issues it makes me wonder if i somehow have a bad ram slot? But then again i never had any issues (yet).

It would be unfortunate if this does indeed have a faulty or failing ram slot as replacing it pr the entire motherboard is more of a hassle than just buying another one of these models. I find myself using this laptop much more than my i5 and i7 laptops which are much faster and hardly used, so i hope it doesn't fail soon because i use it as my main for most of my low medium-low tasks i need to use ( which is really what i use a laptop for).