Help! "Unable to write a necessary file..."

I have Vista Ultimate.

When Limewire starts up it says "LimeWire was unable to write a necessary file because you do not have the necessary permissions. Your preferences may not be maintained the next time you start LimeWire, or LimeWire may behave in unexpected ways."

I have a few questions about this problem...
1. What does this mean?
2. How can I fix this problem? I've been having trouble lately accessing some folders, but it's weird because I'm the only user of my computer. How do I fix the permission problems overall?
3. When I try to search for a file, say an audio file, no results show up? And, out of the five connection bars shown in the bottom left corner- I only one? Why is this, when my internet works perfectly fine?

Thanks!