OS X Lion behaving oddly after upgrading to 16GB RAM Just upgraded Early 2011 Macbook Pro w/ 4GB RAM to 16GB RAM. System now sometimes runs smoothly and other times pauses frequently. 

Terminal keeps giving me 'System is low on disk space/memory' error. I have 12GB free disk space and 16GB RAM for God's sake. Activity Monitor says I got 10GB RAM free. So why is it saying I'm low on disk space? Lion also says sometimes that I'm low on disk space. 

This often happens when spotlight finishes indexing, I guess then system think it's low on disk space (even though I have 9 gb free at that point), then it appears that spotlight trashes its index, systems becomes smooth again, spotlight re-indexes, and same thing happens again. 

My theory so far is that if I have 16GB RAM, then the OS is for some reason trying to reserve atleast 16GB Swap Space on disk 'just in case I run out of the 16GB RAM'. 

Is this true? Does this make sense? 

I really don't want to free up more hard drive space. I already have a 128GB SSD which is small enough as is, and 16GB RAM should be plenty enough for the OS' memory needs. 

Thoughts? 

Thanks!
I got the "System is low on disk space/memory" error as well as a number of other intermittent problems when I upgraded my original apple memory.  It turned out to be either bad memory, or marginal timing specs.

Startup disk has no more space available for application memory?

When I put the original memory back in, the problems went away - so try that if you've exhausted your other options.

I did eventually do a little more research and found a 16GB set that very closely matched Apple specs for my early 2011 macbook pro 17 memory, and it's had no problems for several months now.

I suggest trying out the original apple memory and seeing if the problem goes away.  If it does, return the memory you have, and see if you can get a different set that works better.