1) That's none of the kind of freezes I know from LimeWire. I think you really have to worry.

2) If you can't open the options menu, something is very wrong indeed.

3) Try sharing fewer songs. Sharing 6000 songs may work on normal computers but obviously not on yours.

With all those freezes, invisible options and such first thing I'd do is check if I installed the right Java Runtime Environment (should be Sun's 1.3.1 or 1.4). Second thing I'd do is dump LimeWire or the computer, - that kind of behaviour is weird, to say the least.