Chrome crashes some pages; memtest86+ shows errors even after replacing RAM

I recently bought an IBM S51 PC (P4 3.2 GHz / 2 x 512 MB PC3200-400 DDR), with Win7 installed.

Noticed that Chrome aw snap-crashed some webpages, particularly those with Flash it seemed. After exchanging Win with Lubuntu 12.10, Chrome still crashes certain webpages.

Ran memtest86+ which showed RAM errors. These errors persist even though I have replaced RAM!

What can be the cause?