I decided to upgrade my 2010 MacBook Pro to 8GB from 4GB because I was getting a lot of page outs. I bought the memory from Crucial and used their scanner to determine which modules would definitely work with my system. I installed the memory and ever since that I have been experiencing crashing issues where applications lock up one by one and I am unable to quit them or force quit them, until I am forced to do a hard shut down because my entire system is locked up. I decided to check the memory modules were properly fitted, and I noticed that the top slot wouldn't let my module fit properly. The right hand side was out by about 1mm than the left. I tried pushing in the modules and it just wouldn't work, so the top ram module is properly fitted by about 95% and I think that's one possible reason my computer is crashing. However, I put in the memory that came with my computer and I noticed that didn't fit properly either, even though I didn't experience any issues with the stock RAM. I don't know whether the modules are faulty, or if the slot is the problem. Therefore I don't know whether to phone Apple or get the RAM exchanged from Crucial. I also ran the Apple Hardware Test and it didn't find any issues. Would appreciate any help, thank you!