i have noticed a memory problem-bug, after a while all the available memory is occupied!
even if i am using 1GB or 2GB or even 4GB.
i don't see this if only solidcoin client is running or guiminer for BTC.
I might have experienced the same problem as you have been experiencing. After about 180000 shares my computer started stuttering, it was easy to notice especially in Spotify. I have absolutely no clue of what it could be.