Do you experience problems during downloading?
Check your connection in Status and Interface settings window.
Use Test Server in Config > Servers.
We will probably ask you to do a test using only basic settings.
Do you experience problems during repair or unpacking?
Enable +Debug logging in the Status and Interface settings window and share the relevant parts of the log here using [ code ] sections.
FYI Interesting site: http://www.LinuxAteMyRam.com explaining why/how Linux uses all your RAM (for disk caching), and how to see how much RAM is actually free: the last number in the line "buffers/cache:" from "free -m". So: