Ok I'll try that, thanks.
Locking your knees is actually a bad idea. When you get the sensation, you need to brace yourself up against something, or stand in front of your couch, and ride it out, so you can convince yourself you are NOT going to collapse. All goes back to conditioning, like anything else with anxety.
Maybe is is muscle weakness like you said. I'm not sure. Have you talked to you Dr about this yet?
No back problems and my legs don't feel numb or anything. They don't really feel weak either. It's more of a sensation that I can't feel my legs underneath me or something like that. It's a bit hard to describe.
Since you do sit a lot it's best to get up and walk around every 15 or so. It really does help. I do that when I'm on the computer. After about 15 minutes I get up and walk around. I hope this helps. Please give it a try. If it does'nt you may want to see your Dr for a checkup to make sure you don't have a pinched nerve in your lower back. Are you having any back problems along with weak legs?